JarCasting
url-loader
DEPREACTED for v5: please consider to migarte on asset modules.
A loader for webpack which transforms files into base64 URIs.
Getting Started
To begin, you'll need to install url-loader:
$ npm install url-loader --save-dev
url-loader works like file-loader, but can return a DataURL if the file is smaller than a byte limit.
index.js
import img from './image.png';
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.(png|jpg|gif)$/i,
use: [
{
loader: 'url-loader',
options: {
limit: 8192,
},
},
],
},
],
},
};
And run webpack via your preferred method.
Options
| Name | Type | Default | Description |
|---|---|---|---|
limit |
{Boolean|Number|String} |
undefined |
Specifying the maximum size of a file in bytes. |
mimetype |
{Boolean|String} |
based from mime-types | Sets the MIME type for the file to be transformed. |
encoding |
{Boolean|String} |
base64 |
Specify the encoding which the file will be inlined with. |
generator |
{Function} |
() => type/subtype;encoding,base64_data |
You can create you own custom implementation for encoding data. |
fallback |
{String} |
file-loader |
Specifies an alternative loader to use when a target file's size exceeds the limit. |
esModule |
{Boolean} |
true |
Use ES modules syntax. |
limit
Type: Boolean|Number|String Default: undefined
The limit can be specified via loader options and defaults to no limit.
Boolean
Enable or disable transform files into base64.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.(png|jpg|gif)$/i,
use: [
{
loader: 'url-loader',
options: {
limit: false,
},
},
],
},
],
},
};
Number|String
A Number or String specifying the maximum size of a file in bytes. If the file size is equal or greater than the limit file-loader will be used (by default) and all query parameters are passed to it.
Using an alternative to file-loader is enabled via the fallback option.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.(png|jpg|gif)$/i,
use: [
{
loader: 'url-loader',
options: {
limit: 8192,
},
},
],
},
],
},
};
mimetype
Type: Boolean|String Default: based from mime-types
Specify the mimetype which the file will be inlined with. If unspecified the mimetype value will be used from mime-types.
Boolean
The true value allows to generation the mimetype part from mime-types. The false value removes the mediatype part from a Data URL (if omitted, defaults to text/plain;charset=US-ASCII).
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.(png|jpg|gif)$/i,
use: [
{
loader: 'url-loader',
options: {
mimetype: false,
},
},
],
},
],
},
};
String
Sets the MIME type for the file to be transformed.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.(png|jpg|gif)$/i,
use: [
{
loader: 'url-loader',
options: {
mimetype: 'image/png',
},
},
],
},
],
},
};
encoding
Type: Boolean|String Default: base64
Specify the encoding which the file will be inlined with. If unspecified the encoding will be base64.
Boolean
If you don't want to use any encoding you can set encoding to false however if you set it to true it will use the default encoding base64.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.svg$/i,
use: [
{
loader: 'url-loader',
options: {
encoding: false,
},
},
],
},
],
},
};
String
It supports Node.js Buffers and Character Encodings which are ["utf8","utf16le","latin1","base64","hex","ascii","binary","ucs2"].
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.svg$/i,
use: [
{
loader: 'url-loader',
options: {
encoding: 'utf8',
},
},
],
},
],
},
};
generator
Type: Function Default: (mimetype, encoding, content, resourcePath) => mimetype;encoding,base64_content
You can create you own custom implementation for encoding data.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.(png|html)$/i,
use: [
{
loader: 'url-loader',
options: {
// The `mimetype` and `encoding` arguments will be obtained from your options
// The `resourcePath` argument is path to file.
generator: (content, mimetype, encoding, resourcePath) => {
if (/\.html$/i.test(resourcePath)) {
return `data:${mimetype},${content.toString()}`;
}
return `data:${mimetype}${
encoding ? `;${encoding}` : ''
},${content.toString(encoding)}`;
},
},
},
],
},
],
},
};
fallback
Type: String Default: 'file-loader'
Specifies an alternative loader to use when a target file's size exceeds the limit set in the limit option.
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.(png|jpg|gif)$/i,
use: [
{
loader: 'url-loader',
options: {
fallback: require.resolve('responsive-loader'),
},
},
],
},
],
},
};
The fallback loader will receive the same configuration options as url-loader.
For example, to set the quality option of a responsive-loader above use:
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.(png|jpg|gif)$/i,
use: [
{
loader: 'url-loader',
options: {
fallback: require.resolve('responsive-loader'),
quality: 85,
},
},
],
},
],
},
};
esModule
Type: Boolean Default: true
By default, file-loader generates JS modules that use the ES modules syntax. There are some cases in which using ES modules is beneficial, like in the case of module concatenation and tree shaking.
You can enable a CommonJS module syntax using:
webpack.config.js
module.exports = {
module: {
rules: [
{
test: /\.css$/,
use: [
{
loader: 'url-loader',
options: {
esModule: false,
},
},
],
},
],
},
};
Examples
SVG
SVG can be compressed into a more compact output, avoiding base64. You can read about it more here. You can do it using mini-svg-data-uri package.
webpack.config.js
const svgToMiniDataURI = require('mini-svg-data-uri');
module.exports = {
module: {
rules: [
{
test: /\.svg$/i,
use: [
{
loader: 'url-loader',
options: {
generator: (content) => svgToMiniDataURI(content.toString()),
},
},
],
},
],
},
};
Contributing
Please take a moment to read our contributing guidelines if you haven't yet done so.
License
