This is a Webpack loader which resolves goog.provide() and goog.require() statements in Webpack
as if they were regular CommonJS modules.
npm install --save-dev closure-loader
NOTE: This loader is mainly meant for building (probably older) Closure Compiler projects with Webpack and to make a transition to other module systems (CommonJS or ES6) easier.
There are two parts to this loader:
goog.provide()- Basically just creates the given namespace in the local scope of that module
- Any file containing this statement will be added to a map for require lookups
goog.require()- Like
goog.provide()it creates the given namespace in the scope of that module - It finds the corresponding file with the
goog.provide()statement and loads it (see configuration below) - It assigns the value of the namespace from the provide file and assign it to the same namespace in the current module
- Like
In the simplest way you can just use those two statements like you usually would with Google Closure Tools.
NOTE: Usually the Closure compiler simply creates all namespaces on the global scope (i.e. the window object). This is not the case if you use this loader. Every file ("module") has its own scope just like it would have if you used CommonJS syntax.
You can use Closure dependencies in conjunction with CommonJS syntax. You can load any module that uses
goog.provide() with require(), but not the other way round.
// module.js
goog.provide('my.app.module');
my.app.module = function () {
console.log('my module was loaded');
}
// index.js
var module = require('./module.js').my.app.module;
module(); // will output 'my module was loaded' to the consoleIf you use babel you can even use ES6 import syntax. If you have enabled the es6mode in the loader config
the first goog.provide() of each file will be exported as "default" in addition to its full namespace.
// module.js
goog.provide('my.app.module');
my.app.module = function () {
console.log('my module was loaded');
}
// index.js
import module from './module.js';
// is the same as
var module = require('./module.js').default;
// or
var module = require('./module.js').my.app.module;
module(); // will output 'my module was loaded' to the consoleHere is an example Webpack config for this loader:
module.exports = {
entry: {
app: './src/index.js'
},
output: {
path: './build',
filename: '[name].js'
},
module: {
rules: [
{
test: /\/src\/.*\.js$/,
loader: 'closure-loader',
options: {
paths: [
__dirname + '/src',
],
es6mode: true,
watch: true,
fileExt: '.js',
},
exclude: [/node_modules/, /test/]
}
]
},
};Here are the configuration options specific for this loader:
- paths (array): An array of path strings. The loader will search all
*.jsfiles within theses paths forgoog.provide()statements when resolving agoog.require(). You can onlygoog.require()dependencies that can be found under one of these paths. - es6mode (boolean, default: false): If enabled it will add the value of the first
goog.provide()as default export for usage with babel. For this reason it will also export the corresponding flagmodule.exports.__esModule = true - watch (boolean, default: true): If true, the loader will intitialise watchers which check for changes in the mapped files. This is neccesary to be able to delete the internal map cache. But it also makes problems with CI sytstems and build scripts, because the watcher will prevent the process from beeing exited.
- fileExt (string, default: '.js'): Files extension which will be searched for dependency resolving. Support glob pattern syntax.
NOTE: This loader in no way includes or wraps the actual Google Closure Library. If you want to use the Closure Library you will have to include it yourself and ensure correct shimming:
module: {
rules: [
{
test: /google-closure-library\/closure\/goog\/base/,
use: [
'imports-loader?this=>{goog:{}}&goog=>this.goog',
'exports-loader?goog',
],
},
],
},
plugins: [
new webpack.ProvidePlugin({
goog: 'google-closure-library/closure/goog/base',
}),
]- Steven Weingärtner - Original author & maintainer - eXaminator
- Matt Mulder - Current maintainer - mxmul
See also the list of contributors who participated in this project.
![dependabot[bot] avatar](https://avatars.githubusercontent.com/in/29110?v=4 "dependabot[bot]")
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