### Install and Run i18n-check CLI

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Install the i18n-check package as a development dependency. Use 'npx' to run the command if it's not globally installed or if you're not using npm scripts.

```bash
# Ensure package is installed
npm install --save-dev @lingual/i18n-check

# Use npx if not in npm scripts
npx i18n-check --locales translations/ -s en-US

# Or use full path
node_modules/.bin/i18n-check --locales translations/ -s en-US
```

--------------------------------

### FileInfo Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

An example demonstrating how to instantiate the FileInfo type with sample file path, name, and path segments. This is not typically used in the library API.

```typescript
const info: FileInfo = {
  file: 'locales/de-DE/common.json',
  name: 'common.json',
  path: ['locales', 'de-DE']
};
```

--------------------------------

### Example Usage of StandardReporter

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

Example of how to structure a report object.

```typescript
const report: StandardReporter = {
  file: 'locales/de-DE/common.json',
  key: 'greeting',
  msg: 'Missing element argument'
};
```

--------------------------------

### Options Example with default values

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

An example showing an empty Options object, which will result in all options using their default values. This is useful when no specific configuration is needed.

```typescript
const optionsDefault: Options = {};
```

--------------------------------

### Options Example with react-intl format

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

A minimal example of configuring validation options, specifying only the 'react-intl' format. Other options will use their default values.

```typescript
const optionsMinimal: Options = {
  format: 'react-intl'
};
```

--------------------------------

### Install i18n-check with npm

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Install the i18n-check package as a development dependency using npm.

```bash
npm install --save-dev @lingual/i18n-check
```

--------------------------------

### Options Example with i18next format

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

An example of configuring validation options with the 'i18next' format, specifying checks for missing and invalid keys, and defining keys to ignore using wildcard patterns.

```typescript
const options: Options = {
  format: 'i18next',
  checks: ['missingKeys', 'invalidKeys'],
  ignore: ['beta.*', 'internal.key'],
  nextIntlTranslationFnTypeAlias: []
};
```

--------------------------------

### Show Version

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Displays the installed version of the i18n-check tool. Use either the long or short flag.

```bash
i18n-check --version
i18n-check -V
```

--------------------------------

### Install i18n-check with pnpm

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Install the i18n-check package as a development dependency using pnpm.

```bash
pnpm add --save-dev @lingual/i18n-check
```

--------------------------------

### Install i18n-check with Yarn

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Install the i18n-check package as a development dependency using Yarn.

```bash
yarn add --dev @lingual/i18n-check
```

--------------------------------

### Check Undefined Keys with next-intl Format

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-undefined-keys.md

Example for checking undefined keys with the next-intl format. It assumes a setup where translations are namespaced according to next-intl conventions.

```typescript
// Code:
// const t = useTranslations('home');
// t('title');

const sourceFiles = [
  {
    reference: null,
    name: 'locales/en-US/home.json',
    content: { title: 'Home' }
  }
];

const result = await checkUndefinedKeys(
  sourceFiles,
  ['src/**/*.tsx'],
  { format: 'next-intl', checks: ['undefined'] }
);
// {} - 'title' is defined
```

--------------------------------

### Check Undefined Keys with i18next Format

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-undefined-keys.md

This example demonstrates checking for undefined translation keys using the i18next format. It assumes a typical i18next setup with namespaced JSON files.

```typescript
// Code:
// import { useTranslation } from 'i18next';
// const { t } = useTranslation();
// return <div>{t('newFeature.title')}</div>;

const sourceFiles = [
  {
    reference: null,
    name: 'locales/en-US/common.json',
    content: { greeting: 'Hello' }
  }
];

const result = await checkUndefinedKeys(
  sourceFiles,
  ['src/**/*.tsx'],
  { format: 'i18next', checks: ['undefined'] }
);
// {
//   'src/components/Feature.tsx': ['newFeature.title']
// }
```

--------------------------------

### Run only missing keys check

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--only` or `-o` option to specify a single check to run. This example runs only the `missingKeys` check.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -o missingKeys
```

--------------------------------

### Example TranslationFile Structures

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

Demonstrates creating TranslationFile objects. The 'reference' property is used for grouping related files, while 'null' indicates no specific grouping.

```typescript
const file: TranslationFile = {
  reference: 'en-US',
  name: 'locales/de-DE/common.json',
  content: {
    greeting: 'Hallo',
    farewell: 'Auf Wiedersehen'
  }
};

const multiFile: TranslationFile = {
  reference: null,
  name: 'locales/en-US.json',
  content: {
    greeting: 'Hello'
  }
};

```

--------------------------------

### Run only unused keys check

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--only` or `-o` option to specify a single check to run. This example runs only the `unused` check.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -o unused
```

--------------------------------

### Run only undefined keys check

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--only` or `-o` option to specify a single check to run. This example runs only the `undefined` check.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -o undefined
```

--------------------------------

### i18next Context Separator Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Demonstrates how context is appended to a translation key using an underscore.

```typescript
t('key_context')  // Context appended with underscore
```

--------------------------------

### Example ICU Messages

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Provides examples of various ICU message formats including basic, plural, select, nested, and date/time.

```typescript
// Basic
"greeting: {name}"

// Plural
"You have {count, plural, =0 {no items} one {# item} other {# items}}"

// Select
"The {item} is {status, select, active {available} inactive {unavailable}}"

// Nested
"<bold>Welcome {name}!</bold> You have {count, plural, one {# message} other {# messages}}"

// Date/Time
"Sent on {date, date, long} at {time, time, short}"
```

--------------------------------

### Exclude a mix of files and folders

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

The `--exclude` or `-e` option accepts a combination of files and folders. This example excludes a folder and a specific file.

```bash
yarn i18n:check --locales translations/folderExamples -s en-US -e translations/folderExamples/fr/* translations/messageExamples/it.json
```

--------------------------------

### Run missing and invalid keys checks

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--only` or `-o` option to specify multiple checks. This example runs both `missingKeys` and `invalidKeys` checks, which is the default behavior.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -o missingKeys invalidKeys
```

--------------------------------

### Run unused and undefined keys checks

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--only` or `-o` option to specify multiple checks. This example runs both `unused` and `undefined` checks.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -o unused undefined
```

--------------------------------

### Example InvalidTranslationEntry Object

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

Shows an example of an InvalidTranslationEntry, specifying the translation key and the reason for the validation failure.

```typescript
const entry: InvalidTranslationEntry = {
  key: 'greeting',
  msg: 'Missing element argument'
};
```

--------------------------------

### Run only invalid keys check

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--only` or `-o` option to specify a single check to run. This example runs only the `invalidKeys` check.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -o invalidKeys
```

--------------------------------

### Import All Types from @lingual/i18n-check

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

Import all available types from the library for use in your project. Ensure the library is installed.

```typescript
import type {
  Translation,
  CheckResult,
  InvalidTranslationEntry,
  InvalidTranslationsResult,
  TranslationFile,
  FileInfo,
  Options,
  Context
} from '@lingual/i18n-check';
```

--------------------------------

### i18next Hook Usage Examples

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Demonstrates common ways to use the `useTranslation` and `withTranslation` hooks to access the translation function `t`.

```typescript
const { t } = useTranslation();
const { t } = useTranslation('namespace');
const { t } = withTranslation()(Component);
```

--------------------------------

### Example Translation Object

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

Illustrates the structure of a Translation object, showing nested keys and various value types.

```typescript
const translation: Translation = {
  greeting: 'Hello',
  farewell: 'Goodbye',
  count: 42,
  nested: {
    key: 'value'
  }
};
```

--------------------------------

### Custom Parser Component Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/configuration.md

Example of a custom component that wraps the i18next Trans component. This component can be recognized by the --parser-component-functions option.

```tsx
// Wraps Trans component
function MyTransComponent(props) {
  return <Trans {...props} />;
}

// Will be recognized with:
// --parser-component-functions MyTransComponent
<MyTransComponent i18nKey="greeting" />
```

--------------------------------

### i18next Plural Handling Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Illustrates how i18next uses suffixes for plural forms and how to reference them dynamically. The parser normalizes these to a single base key.

```typescript
// Code
const count = 5;
return t(`items_${count === 1 ? 'one' : 'other'}`, { count });

// Normalized to single key reference: 'items'
```

--------------------------------

### i18next Function Call Examples

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Shows different ways to call the `t` function for retrieving translations, including with and without namespaces, and with interpolation arguments.

```typescript
t('translation.key')
t('namespace:translation.key')
t('translation_one', { count: 1 })
t('translation_other', { count: 2 })
```

--------------------------------

### Custom Component Functions for i18next

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-undefined-keys.md

This example demonstrates how to configure checkUndefinedKeys to recognize translation keys used within custom component wrappers for the i18next format.

```typescript
// Code: 
// <MyCustomTransWrapper i18nKey="welcome" />

const result = await checkUndefinedKeys(
  sourceFiles,
  ['src/**/*.tsx'],
  { format: 'i18next', checks: ['undefined'] },
  ['MyCustomTransWrapper']
);
```

--------------------------------

### GitHub Actions workflow for i18n-check

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

A sample GitHub Actions workflow to automate i18n-check. This workflow installs dependencies, builds the project, and runs the i18n-check command, failing the action if issues are found.

```yaml
name: i18n Check
on:
  pull_request:
    branches:
      - main
  push:
    branches:
      - main

jobs:
  i18n-check:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@master

      - name: yarn install & build
        run: |
          yarn install
          yarn build

      - name: yarn i18n-check
        run: |
          yarn i18n-check --locales translations/messageExamples --source en-US
```

--------------------------------

### Check unused and undefined keys with next-intl

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--unused` or `-u` option to find keys present in translation files but not in the codebase, and vice-versa. Requires specifying the `--format` option. This example uses `next-intl`.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -u client/ -f next-intl
```

--------------------------------

### Migrate from Deprecated --check Option

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

The --check option is deprecated and has been replaced by --only or -o. This example shows the migration path from the old to the new option.

```bash
i18n-check --locales <dir> -s <source> --check <checks...>
```

```bash
# Old (deprecated)
i18n-check --locales translations/ -s en-US --check missingKeys

# New (use --only instead)
i18n-check --locales translations/ -s en-US -o missingKeys
```

--------------------------------

### i18next Parser Validation Examples

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Illustrates valid and invalid translation scenarios based on structure, variable presence, plural forms, and tag names.

```typescript
// Valid - same structure
source: "You have {{count}} items"
target: "You haben {{count}} Artikel"
```

```typescript
// Invalid - missing variable
source: "Hello {{name}}"
target: "Hallo"
```

```typescript
// Valid - different plural forms (German has more forms)
source: "{count} items_one, {count} items_other"
target: "{count} items_zero, {count} items_one, {count} items_few"
```

```typescript
// Invalid - wrong tag name
source: "Click <bold>here</bold>"
target: "Klicken <strong>hier</strong>"
```

--------------------------------

### Example CheckResult Object

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

Demonstrates a CheckResult object, mapping locale identifiers to arrays of translation keys that require attention.

```typescript
const result: CheckResult = {
  'de-de': ['missing_key_1', 'missing_key_2'],
  'fr-fr': ['missing_key_1'],
  'es-es': []
};
```

--------------------------------

### Check unused and undefined keys with i18next

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--unused` or `-u` option to find keys present in translation files but not in the codebase, and vice-versa. Requires specifying the `--format` option. This example uses `i18next`.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -u client/ -f i18next
```

--------------------------------

### Check unused and undefined keys with react-intl

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--unused` or `-u` option to find keys present in translation files but not in the codebase, and vice-versa. Requires specifying the `--format` option. This example uses `react-intl`.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -u client/ -f react-intl
```

--------------------------------

### Integrate i18n-check into TypeScript Build

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Incorporate i18n-check into your TypeScript build process. This example shows how to call the CLI tool from a build script, throwing an error if validation fails. This ensures that translations are checked before the build proceeds.

```typescript
// build.ts - include in your build script
import { execSync } from 'child_process';

const checkTranslations = () => {
  try {
    execSync(
      'i18n-check --locales translations/ -s en-US -f i18next',
      { stdio: 'inherit' }
    );
  } catch {
    throw new Error('Translation validation failed');
  }
};

// Run check before build
checkTranslations();
console.log('Building application...');

```

--------------------------------

### Exclude multiple folders

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--exclude` or `-e` option to exclude specific files or folders from checks. This example excludes files from multiple folders using wildcards.

```bash
yarn i18n:check --locales translations/folderExamples -s en-US -e translations/folderExamples/fr/* translations/folderExample/it/*
```

--------------------------------

### Exclude multiple files

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--exclude` or `-e` option to exclude specific files or folders from checks. This example excludes multiple JSON files.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -e translations/messageExamples/fr-fr.json translations/messageExamples/de-at.json
```

--------------------------------

### Check Unused Keys with i18next Format

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-unused-keys.md

Example of using checkUnusedKeys with the 'i18next' format. This format parses TypeScript/JavaScript for hook calls, function calls, and component usage.

```typescript
// Code contains:
// const { t } = useTranslation();
// return <div>{t('greeting')}</div>;

const result = await checkUnusedKeys(
  translationFiles,
  ['src/**/*.tsx'],
  { format: 'i18next', checks: ['unused'] }
);
// { 'locales/en-US.json': ['farewell', 'unused'] }
```

--------------------------------

### next-intl useTranslations Hook

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Examples of using the useTranslations hook to get a translation function, with and without a namespace.

```typescript
const t = useTranslations();
t('key')
```

```typescript
const t = useTranslations('namespace');
t('key')
```

```typescript
// Type alias
type TFunction = ReturnType<typeof useTranslations>;
const fn = (t: TFunction) => t('key');
```

--------------------------------

### Show Help Message

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Displays the help message, listing all available command-line options. Use either the long or short flag.

```bash
i18n-check --help
i18n-check -h
```

--------------------------------

### Build and Run i18n-check

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Build the project using 'pnpm run build' before running any of the following commands. These commands are used to check translations based on different configurations.

```bash
node dist/bin/index.js --locales translations/messageExamples -s en-US
```

```bash
node dist/bin/index.js --locales translations/flattenExamples -s en-US
```

```bash
node dist/bin/index.js --locales translations/i18NextMessageExamples -s en-US -f i18next
```

```bash
node dist/bin/index.js --locales translations/folderExample -s en-US
```

```bash
node dist/bin/index.js --locales translations/multipleFilesFolderExample/ -s en-US
```

```bash
node dist/bin/index.js --locales translations/folderExample,translations/messageExamples -s en-US
```

--------------------------------

### Select Form Syntax

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Demonstrates branching based on selected values with arbitrary option keys.

```icu
{gender, select, male {he} female {she} other {they}}
```

--------------------------------

### Run i18n-check Tests

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Execute the project's test suite using the provided pnpm command.

```bash
pnpm test
```

--------------------------------

### Basic i18n-check usage with source and locales

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Run i18n-check specifying the source locale and the directory containing translation files.

```bash
yarn i18n:check -s en-US --locales translations/
```

--------------------------------

### CheckResult Type Definition and Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-unused-keys.md

Defines the CheckResult type, which is a record of unused keys per translation file, or undefined. An example illustrates the expected output format.

```typescript
type CheckResult = Record<string, string[]> | undefined;
// Example: { 'locales/en-US.json': ['unused_key_1', 'unused_key_2'] }
```

--------------------------------

### i18n-check with locales and source specified

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Run i18n-check specifying the locales directory and the source locale. This is a common configuration.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US
```

--------------------------------

### Example Usage of CheckError

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

Demonstrates catching a CheckError and accessing its location properties.

```typescript
try {
  checkInvalidTranslations(source, targets);
} catch (error) {
  if (error instanceof CheckError) {
    console.error(error.message);
    if (error.location) {
      console.log(
        `Error at line ${error.location.start.line}, ` +
        `column ${error.location.start.column}`
      );
    }
  }
}
```

--------------------------------

### React-intl FormattedMessage Component

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Examples of using the FormattedMessage component with different IDs, default messages, and values.

```jsx
<FormattedMessage id="greeting" defaultMessage="Hello" />
```

```jsx
<FormattedMessage
  id="plural.items"
  defaultMessage="{count, plural, one {item} other {items}}"
  values={{ count: 5 }}
/>
```

--------------------------------

### Basic Command Syntax

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

The fundamental structure for invoking the i18n-check command.

```bash
i18n-check [options]
```

--------------------------------

### Use summary reporter

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--reporter` or `-r` option to override standard error reporting. Passing `summary` prints a summary of missing or invalid keys.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -r summary
```

--------------------------------

### Example InvalidTranslationsResult

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/types.md

Illustrates the structure of an InvalidTranslationsResult, showing errors for specific locales. This is a typical output from validation functions.

```typescript
const result: InvalidTranslationsResult = {
  'de-de': [
    { key: 'greeting', msg: 'Missing element argument' },
    { key: 'items', msg: 'Error in plural: Expected option "one"' }
  ],
  'fr-fr': []
};

```

--------------------------------

### i18next Format - Tag Mismatch

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-invalid-translations.md

This example shows how to identify incorrect HTML tag usage in i18next formatted translations.

```APIDOC
## i18next Format - Tag Mismatch

### Description

This example shows how to identify incorrect HTML tag usage in i18next formatted translations.

### Method

`checkInvalidTranslations`

### Parameters

- **source** (object) - Required - The source translation object.
- **targets** (object) - Required - An object containing target language translations.
- **options** (object) - Optional - Configuration options, including `format: 'i18next'`.

### Request Example

```typescript
const source = {
  richText: 'Click <bold>here</bold>'
};

const targets = {
  'de-de': {
    richText: 'Klicken <strong>hier</strong>' // Wrong tag name
  }
};

const result = checkInvalidTranslations(
  source,
  targets,
  { format: 'i18next' }
);
```

### Response

#### Success Response (object)

An object containing validation results, detailing mismatches per language and key.

#### Response Example

```json
{
  "de-de": [{
    "key": "richText",
    "msg": "Expected tag \"bold\" but received \"strong\""
  }]
}
```
```

--------------------------------

### i18next Format - Variable Mismatch

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-invalid-translations.md

This example demonstrates how `checkInvalidTranslations` detects missing interpolation variables in i18next formatted translations.

```APIDOC
## i18next Format - Variable Mismatch

### Description

This example demonstrates how `checkInvalidTranslations` detects missing interpolation variables in i18next formatted translations.

### Method

`checkInvalidTranslations`

### Parameters

- **source** (object) - Required - The source translation object.
- **targets** (object) - Required - An object containing target language translations.
- **options** (object) - Optional - Configuration options, including `format: 'i18next'`.

### Request Example

```typescript
const source = {
  greeting: 'Hello {{firstName}} {{lastName}}'
};

const targets = {
  'de-de': {
    greeting: 'Hallo {{firstName}}' // Missing {{lastName}}
  }
};

const result = checkInvalidTranslations(
  source,
  targets,
  { format: 'i18next' }
);
```

### Response

#### Success Response (object)

An object containing validation results, detailing mismatches per language and key.

#### Response Example

```json
{
  "de-de": [{
    "key": "greeting",
    "msg": "Error in interpolation: Expected lastName but received undefined"
  }]
}
```
```

--------------------------------

### Verify Locale Directory and Files

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Troubleshoot 'No Translation Files Found' errors by verifying the path to your locale directory and ensuring files exist for the specified source locale.

```bash
# Verify locale directory path
ls translations/
# Check that files match source locale identifier
ls translations/ | grep en-US
```

--------------------------------

### Configure i18n Check for Unused/Undefined Keys

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Ensure that source code analysis for unused or undefined keys is correctly configured. This requires specifying the format, the source directory for analysis, and the types of keys to report.

```bash
# Ensure:
# 1. --format is specified (required for source code analysis)
# 2. --unused with source paths is provided
# 3. --only includes 'unused' and/or 'undefined'

i18n-check \
  --locales translations/ \
  --source en-US \
  --format i18next \
  --unused src/ \
  --only unused undefined
```

--------------------------------

### Basic checkTranslations() Usage

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-translations.md

Demonstrates the basic usage of checkTranslations with source and target files to find missing keys.

```typescript
import { checkTranslations } from '@lingual/i18n-check';

const sourceFiles = [
  {
    reference: 'en-US',
    name: 'locales/en-US/common.json',
    content: { greeting: 'Hello', farewell: 'Goodbye' }
  }
];

const targetFiles = [
  {
    reference: 'en-US',
    name: 'locales/de-DE/common.json',
    content: { greeting: 'Hallo' } // missing 'farewell'
  }
];

const result = checkTranslations(sourceFiles, targetFiles);
// result.missingKeys = { 'locales/de-DE/common.json': ['farewell'] }
```

--------------------------------

### React-intl with Source Code Analysis

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Checks react-intl format translations by analyzing source code for unused and undefined keys. Specify source file patterns for analysis.

```bash
# react-intl format checking unused and undefined keys
i18n-check \
  --locales locales/ \
  --source en-US \
  --format react-intl \
  --unused "src/**/*.{tsx,ts}" \
  --only unused undefined
```

--------------------------------

### React-intl defineMessages()

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Shows how to define messages using defineMessages and then format them using intl.formatMessage.

```typescript
const messages = defineMessages({
  greeting: { id: 'app.greeting', defaultMessage: 'Hello' },
  farewell: { id: 'app.farewell', defaultMessage: 'Goodbye' }
});

intl.formatMessage(messages.greeting)
```

--------------------------------

### Scan Source Code for Usage

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Use the --unused (or -u) option to provide paths for source code scanning to detect unused or undefined translation keys. This requires specifying a --format. It enables 'unused' and 'undefined' checks.

```bash
i18n-check --locales <dir> -s <source> --unused <paths...> -f <format>
```

```bash
i18n-check -l <dir> -s <source> -u <path1> [path2 ...] -f i18next
```

```bash
# Scan src directory with i18next
i18n-check --locales translations/ -s en-US \
  -f i18next \
  -u src/ \
  -o unused
```

```bash
# Scan multiple directories
i18n-check --locales translations/ -s en-US \
  -f react-intl \
  -u src/ components/ \
  -o unused undefined
```

```bash
# With glob patterns
i18n-check --locales translations/ -s en-US \
  -f next-intl \
  -u "src/**/*.{ts,tsx}" \
  -o unused undefined
```

--------------------------------

### Check invalid translations with options

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use `checkInvalidTranslations` to find invalid keys in target files. This example includes options to specify the 'i18next' format for validation.

```typescript
import { checkInvalidTranslations } from '@lingual/i18n-check';

const options = {
  format: 'i18next',
};

const result = checkInvalidTranslations(source, targets, options);

// {
//  "de-de": ["invalid_translation_key", "some_other_invalid_translation_key"],
//  "fr-fr": [],
// };
```

--------------------------------

### i18next Interpolation Syntax

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Demonstrates basic variable interpolation using double curly braces.

```plaintext
Hello {{name}}
```

--------------------------------

### Exclude a single file

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--exclude` or `-e` option to exclude specific files or folders from checks. This example excludes a single JSON file.

```bash
yarn i18n:check --locales translations/messageExamples -s en-US -e translations/messageExamples/fr-fr.json
```

--------------------------------

### i18next Format - Variable Mismatch Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-invalid-translations.md

Shows how to identify missing interpolation variables in i18next formatted translations. This check is enabled by setting the format option to 'i18next'.

```typescript
const source = {
  greeting: 'Hello {{firstName}} {{lastName}}'
};

const targets = {
  'de-de': {
    greeting: 'Hallo {{firstName}}' // Missing {{lastName}}
  }
};

const result = checkInvalidTranslations(
  source,
  targets,
  { format: 'i18next' }
);
// {
//   'de-de': [{
//     key: 'greeting',
//     msg: 'Error in interpolation: Expected lastName but received undefined'
//   }]
// }
```

--------------------------------

### Check translations with custom options

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `checkTranslations` function to validate source and target locales. This example demonstrates setting the format to 'i18next' for specific validation rules.

```typescript
import { checkTranslations } from '@lingual/i18n-check';

const options = {
  format: 'i18next',
};

const { invalidKeys, missingKeys } = checkTranslations(
  source,
  targets,
  options
);
```

--------------------------------

### Run i18n-check directly via node_modules

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Execute the i18n-check command directly from the local node_modules/.bin directory.

```bash
node_modules/.bin/i18n-check
```

--------------------------------

### Scan Source Code for Unused Keys

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/configuration.md

Use the --unused or -u flag to specify source code paths for scanning translation key usage. This option requires a --format to be specified and enables 'unused' and 'undefined' checks. Glob patterns are accepted.

```bash
i18n-check --locales translations/ -s en-US -u src/ -f i18next
i18n-check --locales translations/ -s en-US -u src/ components/ -f react-intl
```

--------------------------------

### Invalid Translation: Wrong Element Type

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/errors.md

This error occurs when the element types in the source and target translations do not match. For example, the source has a plural element, but the target has a simple argument.

```typescript
// Source: count: '{count, plural, one {item} other {items}}'
// Target: count: '{count}'
// Error: Expected element of type "plural" but received "argument"
```

--------------------------------

### ICU Format - Argument Mismatch Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-invalid-translations.md

Demonstrates how to use checkInvalidTranslations to detect missing variables in ICU formatted translations. Ensure all source variables are present in target translations.

```typescript
import { checkInvalidTranslations } from '@lingual/i18n-check';

const source = {
  greeting: 'Hello {name}'
};

const targets = {
  'de-de': { greeting: 'Hallo' } // Missing {name} variable
};

const result = checkInvalidTranslations(source, targets);
// {
//   'de-de': [{
//     key: 'greeting',
//     msg: 'Missing element argument'
//   }]
// }
```

--------------------------------

### Module Organization in i18n-check

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/README.md

Illustrates the directory structure and main modules of the i18n-check project. Useful for understanding the codebase organization.

```tree
src/
├── index.ts                 # Main API entry point
├── types.ts                 # Type definitions
├── errorReporters.ts        # CLI output formatting
├── bin/
│   └── index.ts             # CLI entry point
└── utils/
    ├── findMissingKeys.ts        # Missing key detection
    ├── findInvalidTranslations.ts # ICU format validation
    ├── findInvalidI18NextTranslations.ts # i18next validation
    ├── flattenTranslations.ts    # Object flattening
    ├── i18NextParser.ts          # i18next message parser
    ├── i18NextSrcParser.ts       # i18next source code analyzer
    ├── nextIntlSrcParser.ts      # next-intl source analyzer
    └── constants.ts              # Constants (plural suffixes)
```

--------------------------------

### i18next Nesting Syntax

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/format-parsers.md

Demonstrates nesting of translation keys using `$t()` or the nesting operator.

```plaintext
Save {{defaultSave}} or load a {{loadData}}
```

```plaintext
Level 1: $t(level2.key)
```

```plaintext
Title: $t(nsWithFeature) items
```

--------------------------------

### ICU Format - Plural Mismatch Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-invalid-translations.md

Illustrates detecting missing plural cases in ICU formatted translations. The checker verifies that all plural options defined in the source exist in the target.

```typescript
const source = {
  items: '{count, plural, one {# item} other {# items}}'
};

const targets = {
  'de-de': {
    items: '{count, plural, one {# artikel}}'
    // Missing 'other' case
  }
};

const result = checkInvalidTranslations(source, targets);
// {
//   'de-de': [{
//     key: 'items',
//     msg: 'Error in plural: Expected option "other" but missing'
//   }]
// }
```

--------------------------------

### i18n-check with i18next format

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Run i18n-check specifying the source locale, locales directory, and the i18next format for validation.

```bash
yarn i18n:check --locales translations/i18NextMessageExamples -s en-US -f i18next
```

--------------------------------

### Exclude a single folder

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use the `--exclude` or `-e` option to exclude specific files or folders from checks. This example excludes all files within a specific folder using a wildcard.

```bash
yarn i18n:check --locales translations/folderExamples -s en-US -e translations/folderExamples/fr/*
```

--------------------------------

### i18next Format - Tag Mismatch Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-invalid-translations.md

Demonstrates detecting incorrect HTML tag names in i18next formatted translations. The checker ensures that opening and closing tags match between source and target.

```typescript
const source = {
  richText: 'Click <bold>here</bold>'
};

const targets = {
  'de-de': {
    richText: 'Klicken <strong>hier</strong>' // Wrong tag name
  }
};

const result = checkInvalidTranslations(
  source,
  targets,
  { format: 'i18next' }
);
// {
//   'de-de': [{
//     key: 'richText',
//     msg: 'Expected tag "bold" but received "strong"'
//   }]
// }
```

--------------------------------

### Next-intl Type Alias Example

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/configuration.md

Demonstrates how to use a type alias for the return type of next-intl's useTranslations. The parser needs the alias name specified via --next-intl-translation-fn-type-alias to recognize translation calls.

```typescript
// Without type alias (always recognized):
const t = useTranslations('home');
const text = t('title');

// With type alias (needs --next-intl-translation-fn-type-alias):
type TFunction = ReturnType<typeof useTranslations>;

const indirectCall = (t: TFunction) => {
  return t('title');
};

// Use: --next-intl-translation-fn-type-alias TFunction
```

--------------------------------

### Add i18n:check script to package.json

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Define a package.json script to easily run the i18n-check command.

```json
"scripts": {
    // ...other commands,
    "i18n:check": "i18n-check"
}
```

--------------------------------

### i18n-check with Single Locale Folder

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Configure i18n-check to process locales from a single directory using the --locales option. Specify the base/reference file with the -s or --source option for comparison.

```bash
yarn i18n:check --locales locales -s locales/en-us.json
```

--------------------------------

### Basic API Options Object

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/configuration.md

A fundamental configuration object for programmatic use. Specify the format, checks to perform, and patterns to ignore.

```typescript
const options: Options = {
  format: 'i18next',
  checks: ['missingKeys', 'invalidKeys'],
  ignore: ['beta.feature.*']
};
```

--------------------------------

### Check Unused Keys with react-intl Format

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/api-reference/check-unused-keys.md

Demonstrates how to use checkUnusedKeys for the 'react-intl' format. Ensure translation files and source files are correctly specified.

```typescript
import { checkUnusedKeys } from '@lingual/i18n-check';

const translationFiles = [
  {
    reference: null,
    name: 'locales/en-US.json',
    content: {
      greeting: 'Hello',
      farewell: 'Goodbye',
      unused: 'This key is not used'
    }
  }
];

const filesToParse = ['src/**/*.tsx', 'src/**/*.ts'];

const result = await checkUnusedKeys(
  translationFiles,
  filesToParse,
  { format: 'react-intl', checks: ['unused'] }
);
// { 'locales/en-US.json': ['unused'] }
```

--------------------------------

### TypeScript Example with ReturnType for Indirect Function Calls

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

This TypeScript code demonstrates an indirect function call where the translation function type is inferred using ReturnType<typeof useTranslations>. This is a standard way to handle translations within components.

```typescript
const indirectFnCall = (
  t: ReturnType<typeof useTranslations<'SomeNameSpace'>>
) => {
  const indirectTranslation = t('someKey');
  // Do something with the indirectTranslation
};

```

--------------------------------

### Run i18n-check CLI with multiple folders

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

Use this command to check locales across multiple specified folders. The `-l` flag indicates the folders containing locales, and `-s` specifies the source locale directory.

```bash
yarn i18n:check -l spaceOne spaceTwo -s en-US
```

--------------------------------

### Run i18n-check in Node.js Script

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Execute i18n-check as a child process within a Node.js script. This is useful for integrating translation checks directly into your application's workflow or build scripts. Ensure 'i18n-check' is installed globally or locally.

```javascript
// Run i18n-check via child process
const { execSync } = require('child_process');

try {
  execSync('i18n-check --locales translations/ -s en-US', {
    stdio: 'inherit'
  });
  console.log('✓ All translations valid');
} catch (error) {
  console.error('✗ Translation validation failed');
  process.exit(1);
}
```

--------------------------------

### Run CLI Validation

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/README.md

Use the CLI for CI/CD pipelines, pre-commit hooks, or one-off validation runs. Specify the locales directory, source locale, and format parser.

```bash
i18n-check --locales translations/ -s en-US -f i18next
```

--------------------------------

### TypeScript Example with Next-Intl Type Alias for Indirect Function Calls

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

This TypeScript code shows how to handle indirect function calls in a next-intl codebase when a type alias is used for the translation function. The --next-intl-translation-fn-type-alias option in i18n-check can be configured to recognize these aliases.

```typescript
import { NextIntlTranslateFnAlias } from './types';

const indirectFnCall = (t: NextIntlTranslateFnAlias<'SomeNameSpace'>) => {
  const indirectTranslation = t('someKey');
  // Do something with the indirectTranslation
};

```

--------------------------------

### Specify Allowed i18n Formats

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/cli-reference.md

Use the '-f' or '--format' flag to specify the translation file format. This is crucial for source code analysis features like detecting unused or undefined keys.

```bash
# Use only allowed formats
-f icu          # Default
-f i18next      # For i18next library
-f react-intl   # For react-intl
-f next-intl    # For next-intl
```

--------------------------------

### Check Missing Keys Only

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/configuration.md

Use this command to find only the translation keys that are missing in the specified locales. Ensure the locales directory and source locale are correctly set.

```bash
i18n-check --locales translations/ -s en-US -o missingKeys
```

--------------------------------

### i18n-check with Folders Per Locale

Source: https://github.com/lingualdev/i18n-check/blob/main/README.md

When locales are organized in subfolders, each containing a single locale file, specify the parent directory with --locales and the source locale folder name with -s. The tool will automatically find corresponding files.

```bash
yarn i18n:check --locales locales -s en-US
```

--------------------------------

### Check All Formats with Ignored Keys

Source: https://github.com/lingualdev/i18n-check/blob/main/_autodocs/configuration.md

This command performs a comprehensive check including missing and invalid keys, while ignoring specific keys or patterns. Use the -i flag for patterns or exact key names to exclude from the check.

```bash
i18n-check --locales translations/ -s en-US \
  -i "features.beta.*" "internal.admin" \
  -o missingKeys invalidKeys
```