### Development Workflow Setup and Execution Source: https://github.com/tc39/ecma262/blob/main/_autodocs/build-system.md Installs dependencies and starts the build process in watch mode for development. Automatically refreshes the browser on file changes. ```bash # Setup npm install # Watch mode (terminal 1) npm run watch # Edit spec.html # Browser automatically refreshes as changes are saved # When ready to publish npm run format # Auto-format markup npm run check-commit # Validate commit messages npm run build # Final production build ``` -------------------------------- ### Clone and Setup Repository Source: https://github.com/tc39/ecma262/blob/main/_autodocs/quick-reference.md Clone the ECMAScript repository and install its dependencies to begin development. The 'watch' command provides a live-reload development environment. ```bash git clone https://github.com/tc39/ecma262.git cd ecma262 npm install npm run watch ``` -------------------------------- ### Install Node.js on Windows Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Installs Node.js using Chocolatey on Windows. ```bash # Windows choco install nodejs ``` -------------------------------- ### Install Node.js on Linux Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Installs Node.js and npm using apt-get on Ubuntu/Debian. ```bash # Linux (Ubuntu/Debian) sudo apt-get install nodejs npm ``` -------------------------------- ### Verify Git Installation Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Checks the installed Git version. ```bash git --version ``` -------------------------------- ### Verify Bibliography Installation Source: https://github.com/tc39/ecma262/blob/main/_autodocs/biblio-package.md After installing the @tc39/ecma262-biblio package, verify its installation using npm. ```bash npm install @tc39/ecma262-biblio npm ls @tc39/ecma262-biblio # Verify installation ``` -------------------------------- ### Clone Repository and Install Dependencies Source: https://github.com/tc39/ecma262/blob/main/_autodocs/development-tools.md Clone the ECMA-262 repository, navigate into the directory, install project dependencies using npm, and set up build and watch scripts. ```bash git clone https://github.com/tc39/ecma262.git cd ecma262 npm install npm run build npm run watch ``` -------------------------------- ### Pre-push Hook Script Example Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Example script for a pre-push hook that validates commit messages and builds the project. ```bash #!/bin/bash npm run check-commit || exit 1 npm run build || exit 1 ``` -------------------------------- ### Install Node.js on macOS Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Installs Node.js using Homebrew on macOS. ```bash # macOS brew install node ``` -------------------------------- ### Verify Node.js Installation Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Checks the installed Node.js version. ```bash node --version ``` -------------------------------- ### Verify npm Installation Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Checks the installed npm version. ```bash npm --version ``` -------------------------------- ### RegExp.prototype.exec() Example with Alternatives Source: https://github.com/tc39/ecma262/blob/main/spec.html Demonstrates how the RegExp.prototype.exec() method handles alternatives when a shorter match is found first. ```javascript /a|ab/.exec("abc") ``` -------------------------------- ### Pre-commit Hook Script Example Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Example script for a pre-commit hook that formats code and checks commit messages. ```bash #!/bin/bash npm run format npm run check-commit ``` -------------------------------- ### String.prototype.localeCompare Canonical Equivalence Examples Source: https://github.com/tc39/ecma262/blob/main/spec.html Demonstrates how String.prototype.localeCompare recognizes and honors canonical equivalence according to the Unicode Standard. These examples show comparisons of characters that may look different but are considered equivalent. ```javascript "\u212B".localeCompare("A\u030A") ``` ```javascript "\u2126".localeCompare("\u03A9") ``` ```javascript "\u1E69".localeCompare("s\u0307\u0323") ``` ```javascript "\u1E0B\u0323".localeCompare("\u1E0D\u0307") ``` ```javascript "\u1100\u1161".localeCompare("\uAC00") ``` -------------------------------- ### Install Prince on macOS Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Installs the Prince HTML to PDF converter on macOS using Homebrew. ```bash # macOS brew install prince ``` -------------------------------- ### Valid Commit Message Examples Source: https://github.com/tc39/ecma262/blob/main/_autodocs/workflow.md Examples of correctly formatted commit messages for various types of changes. ```text Normative: Fix Array.prototype.splice to handle sparse arrays (#3456) Editorial: Clarify grammar in 12.2.1 (#3456) Meta: Add TypeScript definitions to build (#3456) Markup: Add cross-reference IDs to clause 8.1 (#3456) Layering: Add ArrayBuffer alignment requirements (#3456) ``` -------------------------------- ### Function Constructor Examples Source: https://github.com/tc39/ecma262/blob/main/spec.html Demonstrates different ways to invoke the `Function` constructor with varying argument formats for parameters and body. ```javascript new Function("a", "b", "c", "return a+b+c") ``` ```javascript new Function("a, b, c", "return a+b+c") ``` ```javascript new Function("a,b", "c", "return a+b+c") ``` -------------------------------- ### Main Module Example Source: https://github.com/tc39/ecma262/blob/main/FAQ.md This is the entry point module that imports and uses the isOdd function, initiating the module loading and evaluation process. ```javascript import {isOdd} from "./Odd"; isOdd(2); ``` -------------------------------- ### RegExp Constructor Initialization Steps Source: https://github.com/tc39/ecma262/blob/main/spec.html Outlines the steps performed when the RegExp constructor is called, including handling existing RegExp objects and initializing new ones. ```ecmascript 1. Let _patternIsRegExp_ be ? IsRegExp(_patternOrRegexp_). 2. If NewTarget is *undefined*, then 1. Let _newTarget_ be the active function object. 3. If _patternIsRegExp_ is *true* and _flags_ is *undefined*, then 1. Let _patternCtor_ be ? Get(_patternOrRegexp_, "constructor"). 2. If SameValue(_newTarget_, _patternCtor_) is *true*, return _patternOrRegexp_. 4. Else, 1. Let _newTarget_ be NewTarget. 5. If _patternOrRegexp_ is an Object and _patternOrRegexp_ has a [[RegExpMatcher]] internal slot, then 1. Let _patternSource_ be _patternOrRegexp_.[[OriginalSource]]. 2. If _flags_ is *undefined*, set _flags_ to _patternOrRegexp_.[[OriginalFlags]]. 6. Else if _patternIsRegExp_ is *true*, then 1. Let _patternSource_ be ? Get(_patternOrRegexp_, "source"). 2. If _flags_ is *undefined*, then 1. Set _flags_ to ? Get(_patternOrRegexp_, "flags"). 7. Else, 1. Let _patternSource_ be _patternOrRegexp_. 8. Let _obj_ be ? RegExpAlloc(_newTarget_). 9. Return ? RegExpInitialize(_obj_, _patternSource_, _flags_). ``` -------------------------------- ### Format and Build Specification Source: https://github.com/tc39/ecma262/blob/main/_autodocs/quick-reference.md Run these commands to format the specification files and build the output. This is a common step after making editorial or normative changes. ```bash npm run format npm run build ``` -------------------------------- ### Invalid Commit Message Examples Source: https://github.com/tc39/ecma262/blob/main/_autodocs/workflow.md Examples of incorrectly formatted commit messages that would fail validation. ```text Fix Array.prototype.splice # Missing prefix and PR number Normative: Fix Array.prototype.splice # Missing PR number Fix array splice (#3456) # Missing prefix Normative: Fix Array.prototype.splice (#abc) # PR number not integer ``` -------------------------------- ### Expanded '?' Shorthand Example Source: https://github.com/tc39/ecma262/blob/main/spec.html Shows the step-by-step expansion of the '?' shorthand when used in conjunction with another operation, demonstrating the unwrapping and propagation logic. ```ecmascript 1. Perform AO(? Other()). ``` -------------------------------- ### GitHub Actions Build and Test Job Source: https://github.com/tc39/ecma262/blob/main/_autodocs/configuration.md Example commands for building and testing the project in a GitHub Actions workflow. ```bash npm run build npm run test ``` -------------------------------- ### Built-in Method Description Format Source: https://github.com/tc39/ecma262/blob/main/_autodocs/specification-format.md Illustrates the standard format for documenting built-in methods, including their signature, description, notes, algorithm steps, and examples. ```html

Array.prototype.concat ( ...items )

When the concat method is called with zero or more arguments...

This is a non-normative note explaining the behavior.

 1. Let _O_ be ? ToObject(*this* value). 2. ... more steps ...

Example code:


    [1,2,3].concat([4,5])  // [1,2,3,4,5]
``` -------------------------------- ### Type Specification Example Source: https://github.com/tc39/ecma262/blob/main/_autodocs/specification-format.md Demonstrates how to define types and their states using standard HTML paragraph and unordered list elements. ```html

A Promise is an object that represents the eventual completion (or failure) of an asynchronous operation and its resulting value.

A Promise is in one of three states:

``` -------------------------------- ### JSDOM Example Usage Source: https://github.com/tc39/ecma262/blob/main/_autodocs/development-tools.md Example of using JSDOM to parse an HTML file, manipulate the DOM, and serialize it back to a string. ```javascript const { JSDOM, VirtualConsole } = require('jsdom'); // Parse HTML file let dom = await JSDOM.fromFile(file, { contentType: 'text/html; charset=utf-8', virtualConsole }); // Manipulate DOM const { document } = dom.window; document.head.append(style); // Serialize back fs.writeFileSync(file, dom.serialize(), 'utf8'); ``` -------------------------------- ### StatementList Value Example Source: https://github.com/tc39/ecma262/blob/main/spec.html The value of a StatementList is the value of the last value-producing item. Examples demonstrate this with empty statements and variable declarations. ```javascript eval("1;;;;;") eval("1;{}") eval("1;var a;") ``` -------------------------------- ### Load Bibliography via Configuration File Source: https://github.com/tc39/ecma262/blob/main/_autodocs/biblio-package.md Configure ecmarkup to load the ECMA-262 bibliography using a JSON configuration file. ```json { "spec": "spec.html", "loadBiblio": ["@tc39/ecma262-biblio"] } ``` -------------------------------- ### Odd.js Module Example Source: https://github.com/tc39/ecma262/blob/main/FAQ.md This module exports an isOdd function that depends on isEven from another module. It completes the cyclic dependency example. ```javascript import {isEven} from "./Even.js"; export function isOdd(num) { if (num === 0) { return false; } else { return isEven(num - 1); } } ``` -------------------------------- ### GitHub Secrets Configuration Example Source: https://github.com/tc39/ecma262/blob/main/_autodocs/github-configuration.md Example of secrets configured in repository settings. These are available to workflows, actions, and scripts, but are automatically masked in logs. ```yaml GH_TOKEN = ghp_xxxxxxxxxxxxxxxxxxxxxxxxxxxx GOOGLE_API_KEY = AIzaSy_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx ``` -------------------------------- ### Load Bibliography via Command Line Source: https://github.com/tc39/ecma262/blob/main/_autodocs/biblio-package.md Use this command to load the ECMA-262 bibliography when building a specification with ecmarkup. ```bash ecmarkup spec.html output.html --load-biblio @tc39/ecma262-biblio ``` -------------------------------- ### Non-normative Code Example with emu-example Source: https://github.com/tc39/ecma262/blob/main/_autodocs/specification-format.md Includes a non-normative code example using the element, typically containing a 
 block. This is for illustrative purposes and not part of the normative specification.

```javascript
const arr = [1, 2, 3];
console.log(arr.concat([4, 5])); // [1, 2, 3, 4, 5]
```

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

### String.prototype.substring

Source: https://github.com/tc39/ecma262/blob/main/spec.html

Returns a substring of the string, from the start index up to (but not including) the end index. Handles NaN, negative, and out-of-bounds indices by clamping them to the string's length or zero. If start is greater than end, the arguments are swapped.

```APIDOC
## String.prototype.substring

### Description
Returns a substring of the result of converting this object to a String, starting from index `_start_` and running to, but not including, index `_end_` of the String (or through the end of the String if `_end_` is *undefined*). The result is a String value, not a String object.

If either argument is *NaN* or negative, it is replaced with zero; if either argument is strictly greater than the length of the String, it is replaced with the length of the String.

If `_start_` is strictly greater than `_end_`, they are swapped.

### Parameters
#### Path Parameters
None

#### Query Parameters
None

#### Request Body
None

### Method
`substring(_start_, _end_)`

### Endpoint
N/A (This is a prototype method)

### Request Example
N/A

### Response
#### Success Response
- **Return Value** (string) - The extracted substring.

#### Response Example
N/A
```

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

### Module Execution Steps

Source: https://github.com/tc39/ecma262/blob/main/spec.html

This pseudocode outlines the steps for executing an ECMAScript module, including resolving indirect exports, setting up the module environment, and processing import entries.

```ecmascript
1. For each ExportEntry Record _e_ of _module.[[IndirectExportEntries]], do
    1. Assert: _e.[[ExportName]] is not *null*.
    1. Let _resolution_ be _module.ResolveExport(_e.[[ExportName]]).
    1. If _resolution_ is either *null* or ~ambiguous~, throw a *SyntaxError* exception.
    1. Assert: _resolution_ is a ResolvedBinding Record.
    1. Assert: All named exports from _module_ are resolvable.
    1. Let _realm_ be _module.[[Realm]].
    1. Assert: _realm_ is not *undefined*.
    1. Let _envRecord_ be NewModuleEnvironment(_realm.[[GlobalEnv]]).
    1. Set _module.[[Environment]] to _envRecord_.
    1. For each ImportEntry Record _in_ of _module.[[ImportEntries]], do
        1. Let _importedModule_ be GetImportedModule(_module, _in.[[ModuleRequest]]).
        1. If _in.[[ImportName]] is ~namespace~, then
            1. Let _namespace_ be GetModuleNamespace(_importedModule_).
            1. Perform ! _envRecord_.CreateImmutableBinding(_in.[[LocalName]], *true*).
            1. Perform ! _envRecord_.InitializeBinding(_in.[[LocalName]], _namespace_).
        1. Else,
            1. Assert: _in.[[ImportName]] is a String.
            1. Let _resolution_ be _importedModule_.ResolveExport(_in.[[ImportName]]).
            1. If _resolution_ is either *null* or ~ambiguous~, throw a *SyntaxError* exception.
            1. If _resolution.[[BindingName]] is ~namespace~, then
                1. Let _namespace_ be GetModuleNamespace(_resolution.[[Module]]).
                1. Perform ! _envRecord_.CreateImmutableBinding(_in.[[LocalName]], *true*).
                1. Perform ! _envRecord_.InitializeBinding(_in.[[LocalName]], _namespace_).
            1. Else,
                1. Perform CreateImportBinding(_envRecord_, _in.[[LocalName]], _resolution.[[Module]], _resolution.[[BindingName]]).
    1. Let _moduleContext_ be a new ECMAScript code execution context.
    1. Set the Function of _moduleContext_ to *null*.
    1. Assert: _module.[[Realm]] is not *undefined*.
    1. Set the Realm of _moduleContext_ to _module.[[Realm]].
    1. Set the ScriptOrModule of _moduleContext_ to _module_.
    1. Set the VariableEnvironment of _moduleContext_ to _module.[[Environment]].
    1. Set the LexicalEnvironment of _moduleContext_ to _module.[[Environment]].
    1. Set the PrivateEnvironment of _moduleContext_ to *null*.
    1. Set _module.[[Context]] to _moduleContext_.
    1. Push _moduleContext_ onto the execution context stack; _moduleContext_ is now the running execution context.
    1. Let _code_ be _module.[[ECMAScriptCode]].
    1. Let _variableDecls_ be the VarScopedDeclarations of _code_.
    1. Let _declaredVariableNames_ be a new empty List.
    1. For each element _d_ of _variableDecls_, do
        1. For each element _dn_ of the BoundNames of _d_, do
            1. If _declaredVariableNames_ does not contain _dn_, then
                1. Perform ! _envRecord_.CreateMutableBinding(_dn_, *false*).
                1. Perform ! _envRecord_.InitializeBinding(_dn_, *undefined*).
                1. Append _dn_ to _declaredVariableNames_.
    1. Let _lexicalDecls_ be the LexicallyScopedDeclarations of _code_.
    1. Let _privateEnv_ be *null*.
    1. For each element _d_ of _lexicalDecls_, do
        1. For each element _dn_ of the BoundNames of _d_, do
            1. If IsConstantDeclaration of _d_ is *true*, then
                1. Perform ! _envRecord_.CreateImmutableBinding(_dn_, *true*).
            1. Else,
                1. Perform ! _envRecord_.CreateMutableBinding(_dn_, *false*).
            1. If _d_ is either a |FunctionDeclaration|, a |GeneratorDeclaration|, an |AsyncFunctionDeclaration|, or an |AsyncGeneratorDeclaration|, then
                1. Let _funcObj_ be InstantiateFunctionObject of _d_ with arguments _envRecord_ and _privateEnv_.
                1. Perform ! _envRecord_.InitializeBinding(_dn_, _funcObj_).
    1. Remove _moduleContext_ from the execution context stack.
    1. Return ~unused~.
```

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

### Reflect.getPrototypeOf

Source: https://github.com/tc39/ecma262/blob/main/spec.html

Gets the prototype of a specified object.

```APIDOC
## Reflect.getPrototypeOf

### Description
Gets the prototype of a specified object.

### Method
Reflect.getPrototypeOf

### Parameters
- `_target_` (Object) - The object whose prototype to get.

### Returns
The prototype of the specified object.
```

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

### Build All Specification Files

Source: https://github.com/tc39/ecma262/blob/main/_autodocs/README.md

Runs the full build process for the ECMAScript specification, including validation. This is a key script for generating the final specification output.

```bash
npm run build
```

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

### Reflect.get

Source: https://github.com/tc39/ecma262/blob/main/spec.html

Gets the value of a property of an object.

```APIDOC
## Reflect.get

### Description
Gets the value of a property of an object.

### Method
Reflect.get

### Parameters
- `_target_` (Object) - The object from which to get the property value.
- `_key_` (string | symbol) - The name of the property to retrieve.
- `_receiver_` (Object, optional) - The value to use as `this` when getting the property's value.

### Returns
The value of the specified property. If the property does not exist, `undefined` is returned.
```

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

### Lexical Ambiguity Example (Division vs. RegExp)

Source: https://github.com/tc39/ecma262/blob/main/spec.html

Illustrates a scenario where lexical analysis is sensitive to syntactic context, specifically distinguishing between division/division-assignment and regular expression literals. This example shows how ECMAScript avoids semicolon insertion issues.

```javascript
a = b
/hi/g.exec(c).map(d);
```

```javascript
a = b / hi / g.exec(c).map(d);
```