file-replace-loader
v1.4.2
Published
file-replace-loader is webpack loader that allows you replace files in compile time
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file-replace-loader
file-replace-loader is webpack loader that allows you replace files in compile time by some condition.
file-replace-loader is free and will always remain free A simple and quick way to support the project is to buy me a coffee. It will take no more than 5 minutes and will allow the project to keep going
Table of contents
- Features
- Installation
- Usage
- Multiple replace
- Using with binary files
- Using with other loaders
- Loader options
- Contributing
- License
Features
- Compatibility with webpack 3.x, 4.x, 5.x;
- Support watch webpack mode;
- Replace files in compile time without change source files;
- Multiple replacement;
- Sync and async modes;
- Compatibility with other loaders;
- Support binary files.
Installation
NPM
npm install --save-dev file-replace-loader
Yarn
yarn add file-replace-loader
Usage
const { resolve } = require('path');
module.exports = {
//...
module: {
rules: [{
test: /\.config\.js$/,
loader: 'file-replace-loader',
options: {
condition: 'if-replacement-exists',
replacement: resolve('./config.local.js'),
async: true,
}
}]
}
}
This example rule replaces all of imports /\.config.js$/
to config.local.js
file, if replacement exists (condition if-replacement-exists
).
After this build a bundle file will contain code from config.local.js
and original sources
won't changed.
Multiple replace
To describe replace rules for two or more files you can use function as replacement value.
How does it work?
- Webpack runs file-replace-loader according to
test
rule,include
andexclude
rule options; - file-replace-loader looks on
replacement
option. If it is string then the loader just replace a file. If it is a function then file-replace-loader checking what it returns. If the function returns a path to file then the loader replaces, if returns nothing then current match skips. - If
replacement
function returns a path then file-replace-loader looks tocondition
. If condition isalways
then it replace every match. Ifcondition
isif-replacement-exists
then loader checking existing file, etc;
For example:
const { resolve } = require('path');
module.exports = {
//...
module: {
rules: [{
test: /\.js$/,
loader: 'file-replace-loader',
options: {
condition: 'always', // <-- Note that the rule applies for all files!
replacement(resourcePath) {
if (resourcePath.endsWith('foo.js')) {
return resolve('./bar.js');
}
if (resourcePath.endsWith('foo-a.js')) {
return resolve('./bar-a.js');
}
},
async: true,
}
}]
}
}
file-replace-loader passes to replacement
function resourcePath
for every matching.
file-replace-loader doesn't care what developer does with this path but if repalcement
function returns a new path then file-replace-loader replaces file.
If replacement
function returns nothing then file-replace-loading skip replace for current resourcePath
.
Example with mapping:
const { resolve } = require('path');
module.exports = {
//...
module: {
rules: [{
test: /\.js$/,
loader: 'file-replace-loader',
options: {
condition: 'always', // <-- Note that the rule applies for all files! But you can use other conditions too
replacement(resourcePath) {
const mapping = {
[resolve('./src/foo-a.js')]: resolve('./src/bar-a.js'),
[resolve('./src/foo-b.js')]: resolve('./src/bar-b.js'),
[resolve('./src/foo-c.js')]: resolve('./src/bar-c.js'),
};
return mapping[resourcePath];
},
async: true,
}
}]
}
}
NOTE: Make shure that all replacement files contains necessary imports and exports that other files are expecting.
Using with binary files
file-replace-loader allows replace binary files. For example:
//webpack.config.js
const { resolve } = require('path');
module.exports = {
//...
module: {
rules: [{
test: /\.png$/,
use: [{
loader: 'file-loader',
options: {
name: '[name].[ext]',
},
}, {
loader: 'file-replace-loader',
options: {
condition: 'if-replacement-exists',
replacement: resolve('./src/replacement.png')
}
}]
}]
}
}
Using with other loaders
file-replace-loader must executes before other loaders. This means that in webpack config file the loader must be last in list. For example:
//webpack.config.js
const { resolve } = require('path');
// Correct
module.exports = {
//...
module: {
rules: [{
test: /\.config\.js$/,
use: [{
loader: 'babel-loader',
}, {
loader: 'file-replace-loader',
options: {
condition: 'if-replacement-exists',
replacement: resolve('./config.local.js'),
async: true,
}
}]
}]
},
}
Above is correct example. file-replace-loader will executed before other loaders. Let's see incorrect usage:
//webpack.config.js
const { resolve } = require('path');
// Error, because file-replace-loader will be execute after other loaders
module.exports = {
//...
module: {
rules: [{
test: /\.config\.js$/,
use: [{
loader: 'file-replace-loader',
options: {
condition: 'if-replacement-exists',
replacement: resolve('./config.local.js'),
async: true,
}
}, {
loader: 'babel-loader',
}]
}]
},
}
In incorrect example above file-replace-loader first in rule list. This case throw an error because file-replace-loader should be last in list.
Loader options
| Option | Type | Required | Default | Possible values
| ------------ | ------------- | ------------- | ------------- | -------------
| condition
Condition to replace | string
|boolean
| no | 'if-replacement-exists'
| true
,false
,'always'
,'never'
,'if-replacement-exists'
,'if-source-is-empty'
| replacement
Replacement file | string
|function (resourcePath, options)
| yes | — | Full path to file or function returning full path to file
| async
Asynchronous file reading | boolean
| no | true
| true
,false
| progress
Progress output | boolean
| no | IS_DEBUG_MODE == true or IS_PROGRESS_MODE == true
| true
,false
Contributing
See contributing guideline.