replace-in-file

What is replace-in-file?

The replace-in-file npm package allows you to easily search and replace text in files. It is useful for tasks such as updating configuration files, modifying source code, and performing batch text replacements.

What are replace-in-file's main functionalities?

Basic Replacement

This feature allows you to perform a basic search and replace operation in a specified file. The 'from' field can be a string or a regular expression, and the 'to' field is the replacement string.

const replace = require('replace-in-file');

const options = {
  files: 'path/to/file.txt',
  from: /oldText/g,
  to: 'newText',
};

replace(options)
  .then(results => console.log('Replacement results:', results))
  .catch(error => console.error('Error occurred:', error));

Multiple Replacements

This feature allows you to perform multiple search and replace operations in a single file. The 'from' and 'to' fields are arrays, where each element in 'from' is replaced by the corresponding element in 'to'.

const replace = require('replace-in-file');

const options = {
  files: 'path/to/file.txt',
  from: [/oldText1/g, /oldText2/g],
  to: ['newText1', 'newText2'],
};

replace(options)
  .then(results => console.log('Replacement results:', results))
  .catch(error => console.error('Error occurred:', error));

Glob Pattern Matching

This feature allows you to use glob patterns to specify multiple files for the search and replace operation. This is useful for batch processing multiple files in a directory.

const replace = require('replace-in-file');

const options = {
  files: 'path/to/*.txt',
  from: /oldText/g,
  to: 'newText',
};

replace(options)
  .then(results => console.log('Replacement results:', results))
  .catch(error => console.error('Error occurred:', error));

Dry Run

This feature allows you to perform a dry run of the search and replace operation. No actual changes are made to the files, but you can see what the results would be. This is useful for testing your replacement logic before applying it.

const replace = require('replace-in-file');

const options = {
  files: 'path/to/file.txt',
  from: /oldText/g,
  to: 'newText',
  dry: true,
};

replace(options)
  .then(results => console.log('Dry run results:', results))
  .catch(error => console.error('Error occurred:', error));

Other packages similar to replace-in-file

replace

The 'replace' package is another tool for performing search and replace operations in files. It offers similar functionality to 'replace-in-file' but with a simpler API. It is suitable for straightforward replacement tasks.

string-replace-loader

The 'string-replace-loader' package is a webpack loader that allows you to perform string replacements in your source files during the build process. It is useful for replacing text in JavaScript and other files as part of your build pipeline.

gulp-replace

The 'gulp-replace' package is a plugin for the Gulp task runner that allows you to perform search and replace operations in your Gulp streams. It integrates well with Gulp workflows and is useful for automating text replacements in your build process.

README

Replace in file

A simple utility to quickly replace text in one or more files or globs. Works synchronously or asynchronously with either promises or callbacks. Make a single replacement or multiple replacements at once.

Index

• Installation
• Basic usage
  • Asynchronous replacement with async/await
  • Asynchronous replacement with promises
  • Asynchronous replacement with callback
  • Synchronous replacement
  • Return value
• Advanced usage
  • Replace a single file or glob
  • Replace multiple files or globs
  • Replace first occurrence only
  • Replace all occurrences
  • Multiple values with the same replacement
  • Multiple values with different replacements
  • Using callbacks for from
  • Using callbacks for to
  • Ignore a single file or glob
  • Ignore multiple files or globs
  • Allow empty/invalid paths
  • Disable globs
  • Specify glob configuration
  • Specify character encoding
  • Dry run
• CLI usage
• Version information
• License

Installation

# Using npm, installing to local project
npm i --save replace-in-file

# Using npm, installing globally for global cli usage
npm i -g replace-in-file

# Using yarn
yarn add replace-in-file

Basic usage

//Load the library and specify options
const replace = require('replace-in-file');
const options = {
  files: 'path/to/file',
  from: /foo/g,
  to: 'bar',
};

Asynchronous replacement with async/await

try {
  const changes = await replace(options)
  console.log('Modified files:', changes.join(', '));
}
catch (error) {
  console.error('Error occurred:', error);
}

Asynchronous replacement with promises

replace(options)
  .then(changes => {
    console.log('Modified files:', changes.join(', '));
  })
  .catch(error => {
    console.error('Error occurred:', error);
  });

Asynchronous replacement with callback

replace(options, (error, changes) => {
  if (error) {
    return console.error('Error occurred:', error);
  }
  console.log('Modified files:', changes.join(', '));
});

Synchronous replacement

try {
  const changes = replace.sync(options);
  console.log('Modified files:', changes.join(', '));
}
catch (error) {
  console.error('Error occurred:', error);
}

Return value

The return value of the library is an array of file names of files that were modified (e.g. had some of the contents replaced). If no replacements were made, the return array will be empty.

const changes = replace.sync({
  files: 'path/to/files/*.html',
  from: 'foo',
  to: 'bar',
});

console.log(changes);

// [
//   'path/to/files/file1.html',
//   'path/to/files/file3.html',
//   'path/to/files/file5.html',
// ]

Advanced usage

Replace a single file or glob

const options = {
  files: 'path/to/file',
};

Replace multiple files or globs

const options = {
  files: [
    'path/to/file',
    'path/to/other/file',
    'path/to/files/*.html',
    'another/**/*.path',
  ],
};

Replace first occurrence only

const options = {
  from: 'foo',
  to: 'bar',
};

Replace all occurrences

Please note that the value specified in the from parameter is passed straight to the native String replace method. As such, if you pass a string as the from parameter, it will only replace the first occurrence.

To replace multiple occurrences at once, you must use a regular expression for the from parameter with the global flag enabled, e.g. /foo/g.

const options = {
  from: /foo/g,
  to: 'bar',
};

Multiple values with the same replacement

These will be replaced sequentially.

const options = {
  from: [/foo/g, /baz/g],
  to: 'bar',
};

Multiple values with different replacements

These will be replaced sequentially.

const options = {
  from: [/foo/g, /baz/g],
  to: ['bar', 'bax'],
};

Using callbacks for from

You can also specify a callback that returns a string or a regular expression. The callback receives the name of the file in which the replacement is being performed, thereby allowing the user to tailor the search string. The following example uses a callback to produce a search string dependent on the filename:

const options = {
  files: 'path/to/file',
  from: (file) => new RegExp(file, 'g'),
  to: 'bar',
};

Using callbacks for to

As the to parameter is passed to the native String replace method, you can also specify a callback. The following example uses a callback to convert matching strings to lowercase:

const options = {
  files: 'path/to/file',
  from: /SomePattern[A-Za-z-]+/g,
  to: (match) => match.toLowerCase(),
};

This callback provides for an extra argument above the String replace method, which is the name of the file in which the replacement is being performed. The following example replaces the matched string with the filename:

const options = {
  files: 'path/to/file',
  from: /SomePattern[A-Za-z-]+/g,
  to: (...args) => args.pop(),
};

Ignore a single file or glob

const options = {
  ignore: 'path/to/ignored/file',
};

Ignore multiple files or globs

const options = {
  ignore: [
    'path/to/ignored/file',
    'path/to/other/ignored_file',
    'path/to/ignored_files/*.html',
    'another/**/*.ignore',
  ],
};

Please note that there is an open issue with Glob that causes ignored patterns to be ignored when using a ./ prefix in your files glob. To work around this, simply remove the prefix, e.g. use **/* instead of ./**/*.

Allow empty/invalid paths

If set to true, empty or invalid paths will fail silently and no error will be thrown. For asynchronous replacement only. Defaults to false.

const options = {
  allowEmptyPaths: true,
};

Disable globs

You can disable globs if needed using this flag. Use this when you run into issues with file paths like files like //SERVER/share/file.txt. Defaults to false.

const options = {
  disableGlobs: true,
};

Specify glob configuration

Specify configuration passed to the glob call:

const options = {
  glob: {
    //Glob settings here
  },
};

Please note that the setting nodir will always be passed as false.

Specify character encoding

Use a different character encoding for reading/writing files. Defaults to utf-8.

const options = {
  encoding: 'utf8',
};

Dry run

To do a dry run without actually making replacements, for testing purposes. Defaults to false.

const options = {
  dry: true,
};

CLI usage

replace-in-file from to some/file.js,some/**/glob.js
  [--configFile=replace-config.js]
  [--ignore=ignore/files.js,ignore/**/glob.js]
  [--encoding=utf-8]
  [--disableGlobs]
  [--isRegex]
  [--verbose]
  [--dry]

Multiple files or globs can be replaced by providing a comma separated list.

The flags --disableGlobs, --ignore and --encoding are supported in the CLI.

The setting allowEmptyPaths is not supported in the CLI as the replacement is synchronous, and this setting is only relevant for asynchronous replacement.

To list the changed files, use the --verbose flag. To do a dry run, use --dry.

A regular expression may be used for the from parameter by specifying the --isRegex flag.

The from and to parameters, as well as the files list, can be omitted if you provide this information in a configuration file. You can provide a path to a configuration file (either Javascript or JSON) with the --configFile flag. This path will be resolved using Node’s built in path.resolve(), so you can pass in an absolute or relative path.

Version information

From version 3.0.0 onwards, replace in file requires Node 6 or higher. If you need support for Node 4 or 5, please use version 2.x.x.

License

(MIT License)

Copyright 2015-2018, Adam Reis, co-founder at Hello Club