file-loader

What is file-loader?

The file-loader npm package is used to process files such as images, fonts, and other binary assets within a webpack build process. It can copy files to the output directory and resolve import/require() on a file into a url.

What are file-loader's main functionalities?

Importing Images

Allows importing image files directly in JavaScript or TypeScript files. The file-loader processes the import and replaces it with the final path to the output file.

import img from './file.png';

Configuring Output Path and Filenames

Configures webpack to output files with a specific naming pattern and to a specific directory. It also allows setting a public path for the files when they are referenced in the browser.

module.exports = {
  module: {
    rules: [
      {
        test: /\.(png|jpe?g|gif)$/i,
        use: [
          {
            loader: 'file-loader',
            options: {
              name: '[path][name].[ext]',
              outputPath: 'images/',
              publicPath: 'assets/',
            },
          },
        ],
      },
    ],
  },
};

Handling Fonts

Enables the inclusion and processing of font files in various formats. The file-loader will handle these assets and output them to a specified directory.

module.exports = {
  module: {
    rules: [
      {
        test: /\.(woff|woff2|eot|ttf|otf)$/i,
        use: [
          {
            loader: 'file-loader',
            options: {
              name: '[name].[ext]',
              outputPath: 'fonts/',
            },
          },
        ],
      },
    ],
  },
};

Other packages similar to file-loader

url-loader

The url-loader works like the file-loader, but can return a Data URL if the file is smaller than a byte limit. This can reduce the number of HTTP requests for small files.

raw-loader

The raw-loader allows importing files as a string. This is useful for importing things like HTML or SVG directly into your JavaScript code, which is different from file-loader's typical binary asset handling.

copy-webpack-plugin

This plugin allows copying individual files or entire directories to the build directory. It is more flexible than file-loader for simply copying files without processing them through webpack's module system.

README

File Loader

Instructs webpack to emit the required object as file and to return its public url.

Install

npm install --save-dev file-loader

Usage

By default the filename of the resulting file is the MD5 hash of the file's contents with the original extension of the required resource.

var url = require("file-loader!./file.png");
// => emits file.png as file in the output directory and returns the public url
// => returns i. e. "/public-path/0dcbbaa701328a3c262cfd45869e351f.png"

By default a file is emitted, however this can be disabled if required (e.g. for server side packages).

var url = require("file-loader?emitFile=false!./file.png");
// => returns the public url but does NOT emit a file
// => returns i. e. "/public-path/0dcbbaa701328a3c262cfd45869e351f.png"

Filename templates

You can configure a custom filename template for your file using the query parameter name. For instance, to copy a file from your context directory into the output directory retaining the full directory structure, you might use ?name=[path][name].[ext].

By default, the path and name you specify will output the file in that same directory and will also use that same URL path to access the file.

You can specify custom output and public paths by using the outputPath, publicPath and useRelativePath query name parameters:

use: "file-loader?name=[name].[ext]&publicPath=assets/foo/&outputPath=app/images/"

useRelativePath should be true if you wish to generate relative URL to the each file context

{
 loader: 'file-loader',
 query: {
  useRelativePath: process.env.NODE_ENV === "production"
 }
}

Filename template placeholders

• [ext] the extension of the resource
• [name] the basename of the resource
• [path] the path of the resource relative to the context query parameter or option.
• [hash] the hash of the content, hex-encoded md5 by default
• [<hashType>:hash:<digestType>:<length>] optionally you can configure
  • other hashTypes, i. e. sha1, md5, sha256, sha512
  • other digestTypes, i. e. hex, base26, base32, base36, base49, base52, base58, base62, base64
  • and length the length in chars
• [N] the N-th match obtained from matching the current file name against the query param regExp

Examples

require("file-loader?name=js/[hash].script.[ext]!./javascript.js");
// => js/0dcbbaa701328a3c262cfd45869e351f.script.js

require("file-loader?name=html-[hash:6].html!./page.html");
// => html-109fa8.html

require("file-loader?name=[hash]!./flash.txt");
// => c31e9820c001c9c4a86bce33ce43b679

require("file-loader?name=[sha512:hash:base64:7].[ext]!./image.png");
// => gdyb21L.png
// use sha512 hash instead of md5 and with only 7 chars of base64

require("file-loader?name=img-[sha512:hash:base64:7].[ext]!./image.jpg");
// => img-VqzT5ZC.jpg
// use custom name, sha512 hash instead of md5 and with only 7 chars of base64

require("file-loader?name=picture.png!./myself.png");
// => picture.png

require("file-loader?name=[path][name].[ext]?[hash]!./dir/file.png")
// => dir/file.png?e43b20c069c4a01867c31e98cbce33c9

Contributing

Don't hesitate to create a pull request. Every contribution is appreciated. In development you can start the tests by calling npm test.

Maintainers

Juho Vepsäläinen

Joshua Wiens

Kees Kluskens

Sean Larkin

LICENSE

MIT

Changelog

1.0.0-beta.0 (2017-06-07)

Code Refactoring

• Apply webpack-defaults (#167) (632ed72)

BREAKING CHANGES

• Enforces Webpack standard NodeJS engines range. at the time of merge >= 4.3 < 5.0.0 || >= 5.10.

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