This code exports two functions, chext and chroot, which manipulate file paths by changing extensions and checking/file paths. The code uses regular expressions and the path module for these functions.

Run example

npm run import -- "changing file names"

changing file names

var path = require('path')

function chext(file, ext) {
    return file.replace(new RegExp('\\' + path.extname(file) + '


), ext)
}

function chroot(file, root, output) {
    // TODO: example of defensive programming
    if(file.substr(0, root.length).localeCompare(root) !== 0)
        throw new Error(`File not in root ${file}`)
    return path.join(output, file.substr(root.length))
}

module.exports = {
    chext,
    chroot,
}

```javascript
const path = require('path');

/**
 * Changes the file extension.
 * @param {string} file The original file path.
 * @param {string} ext The new file extension.
 * @returns {string} The file path with the new extension.
 */
function changeExtension(file, ext) {
    const originalExtension = path.extname(file);
    return file.replace(new RegExp(`^.*(${originalExtension})



  
  
  
  
  
  



  
  

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  ), `$1${ext}`);
}

/**
 * Changes the root path of a file.
 * @param {string} file The original file path.
 * @param {string} root The root path to check against.
 * @param {string} output The new root path.
 * @returns {string} The file path with the new root.
 * @throws {Error} If the file is not in the specified root.
 */
function changeRoot(file, root, output) {
    if (!file.startsWith(root)) {
        throw new Error(`File not in root ${file}`);
    }
    return path.join(output, file.slice(root.length));
}

module.exports = {
    changeExtension,
    changeRoot,
};
```

Code Breakdown

Overview

This code exports two functions, chext and chroot, which manipulate file paths.

Functions

chext(file, ext)

• Replaces the file extension of file with ext.
• Uses a regular expression to match the file extension of file and replace it with ext.
• Returns the modified file path.

chroot(file, root, output)

• Checks if file starts with root (case-sensitive).
• If file does not start with root, throws an error.
• Otherwise, returns a new file path by joining output and the part of file after root.
• Uses the path module to manipulate file paths.

Module Exports

The code exports an object with the two functions, chext and chroot.

Note

The chroot function has a TODO comment indicating that defensive programming examples are needed.