### Install Dependencies (Batch)

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Installs the required build packages for the QR scanner project using npm. Node.js is a prerequisite for this command.

```batch
npm install
```

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

### Initialize QR Scanner with Webcam and File Input

Source: https://github.com/skbkontur/qr-scanner/blob/master/demo/index.html

Initializes the QRScanner library, sets the worker path, gets references to HTML elements for video and file input, and sets up event listeners for scanning from both a webcam and a file.

```javascript
import QrScanner from "../qr-scanner.min.js";
QrScanner.WORKER_PATH = '../qr-scanner-worker.min.js';

const video = document.getElementById('qr-video');
const camHasCamera = document.getElementById('cam-has-camera');
const camQrResult = document.getElementById('cam-qr-result');
const camQrResultTimestamp = document.getElementById('cam-qr-result-timestamp');
const fileSelector = document.getElementById('file-selector');
const fileQrResult = document.getElementById('file-qr-result');

function setResult(label, result) {
    label.textContent = result;
    camQrResultTimestamp.textContent = new Date().toString();
    label.style.color = 'teal';
    clearTimeout(label.highlightTimeout);
    label.highlightTimeout = setTimeout(() => label.style.color = 'inherit', 100);
}

// ####### Web Cam Scanning #######
QrScanner.hasCamera().then(hasCamera => camHasCamera.textContent = hasCamera);

const scanner = new QrScanner(video, result => setResult(camQrResult, result));
scanner.start();

document.getElementById('inversion-mode-select').addEventListener('change', event => {
    scanner.setInversionMode(event.target.value);
});

// ####### File Scanning #######
fileSelector.addEventListener('change', event => {
    const file = fileSelector.files[0];
    if (!file) {
        return;
    }
    QrScanner.scanImage(file)
        .then(result => setResult(fileQrResult, result))
        .catch(e => setResult(fileQrResult, e || 'No QR code found.'));
});
```

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

### Install QR Scanner with npm or yarn

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Installs the QR Scanner library using either npm or yarn package managers. This is the recommended way to include the library in your project for easy dependency management.

```bash
npm install --save qr-scanner
```

```bash
yarn add qr-scanner
```

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

### Build Project (Batch)

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Builds the QR scanner project. This command is necessary if you need to modify the code in the /src folder. It requires Node.js and previously installed build packages.

```batch
npm run build
```

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

### Initialize QR Scanner for Video Stream

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Creates a new `QrScanner` instance, linking it to an HTML video element and providing a callback function to process decoded QR code results. The page must be served via HTTPS for webcam access.

```javascript
const videoElem = document.querySelector('video');
const qrScanner = new QrScanner(videoElem, result => console.log('decoded qr code:', result));
```

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

### Import QR Scanner ES6 Module

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Demonstrates how to import the main QR Scanner API as an ES6 module. This is used when integrating the library into modern JavaScript projects or build systems.

```javascript
import QrScanner from 'path/to/qr-scanner.min.js'; // if using plain es6 import
import QrScanner from 'qr-scanner'; // if installed via package and bundling with webpack or rollup
```

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

### Configure Worker Path with Webpack

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Shows how to use Webpack's file loader to automatically copy the worker script to your build output and set the `WORKER_PATH` accordingly. This simplifies asset management in Webpack projects.

```javascript
import QrScannerWorkerPath from '!!file-loader!./node_modules/qr-scanner/qr-scanner-worker.min.js';
QrScannerLib.WORKER_PATH = QrScannerWorkerPath;
```

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

### Set QR Scanner Worker Path

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Configures the path to the `qr-scanner-worker.min.js` file, which runs the scanning logic in a separate thread. This is crucial for maintaining UI responsiveness during scanning.

```javascript
QrScanner.WORKER_PATH = 'path/to/qr-scanner-worker.min.js';
```

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

### Scan QR Code from Image

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Scans a QR code from a given image source using the static `scanImage` method. It returns a promise that resolves with the decoded result or rejects if no QR code is found.

```javascript
QrScanner.scanImage(image)
    .then(result => console.log(result))
    .catch(error => console.log(error || 'No QR code found.'));
```

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

### Set QR Scanner Grayscale Weights

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Adjusts the weights for red, green, and blue channels in the grayscale conversion process. This can improve contrast and scanning accuracy for QR codes with specific color characteristics.

```javascript
qrScanner.setGrayscaleWeights(red, green, blue, useIntegerApproximation = true);
```

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

### Set QR Scanner Inversion Mode

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

Configures the QR scanner to detect QR codes with inverted colors (light on dark background) or both (original and inverted). This is useful for handling QR codes with different color schemes.

```javascript
qrScanner.setInversionMode(inversionMode); // inversionMode can be 'original', 'invert', or 'both'
```

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

### Destroy QR Scanner Instance (JavaScript)

Source: https://github.com/skbkontur/qr-scanner/blob/master/README.md

This code snippet demonstrates how to destroy the QR scanner instance, stopping the camera stream, web worker, and cleaning up event listeners. It sets the qrScanner variable to null after destruction.

```javascript
qrScanner.destroy();
qrScanner = null;
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.