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loadjs
Advanced tools
Changelog
3.5.3 - March 21, 2018
Readme
LoadJS is a tiny async loader for modern browsers (747 bytes).
LoadJS is a tiny async loading library for modern browsers (IE9+). It has a simple yet powerful dependency management system that lets you fetch JavaScript and CSS files in parallel and execute code after the dependencies have been met. The recommended way to use LoadJS is to include the minified source code of loadjs.js in your <html> (possibly in the <head> tag) and then use the loadjs
global to manage JavaScript dependencies after pageload.
LoadJS is based on the excellent $script library by Dustin Diaz. We kept the behavior of the library the same but we re-wrote the code from scratch to add support for success/error callbacks and to optimize the library for modern browsers. LoadJS is 747 bytes (minified + gzipped).
Here's an example of what you can do with LoadJS:
// define a dependency bundle
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar');
// execute code when the bundle loads
loadjs.ready('foobar', function() {
/* foo.js & bar.js loaded */
});
// OR use more advanced syntax for more options
loadjs.ready('foobar', {
success: function() { /* foo.js & bar.js loaded */ },
error: function(depsNotFound) { /* foobar bundle load failed */ },
before: function(path, scriptEl) { /* execute code before fetch */ },
async: true, // load files synchronously or asynchronously (default: true)
numRetries: 3 // number of times to retry fetch (default: 0)
});
The latest version of LoadJS can be found in the dist/
directory in this repository:
You can also use it as a CJS or AMD module:
$ npm install --save loadjs
var loadjs = require('loadjs');
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar');
// execute code when the bundle loads
loadjs.ready('foobar', function() {
/* foo.js & bar.js loaded */
});
// OR use more advanced syntax for more options
loadjs.ready('foobar', {
success: function() { /* foo.js & bar.js loaded */ },
error: function(depsNotFound) { /* foobar bundle load failed */ },
before: function(path, scriptEl) { /* execute code before fetch */ },
async: true, // load files synchronously or asynchronously (default: true)
numRetries: 3 // number of times to retry fetch (default: 0)
});
async: false
support only works in IE10+)LoadJS also detects script load failures from AdBlock Plus and Ghostery in:
Note: LoadJS treats empty CSS files as load failures in IE (to get around lack of support for onerror events on <link>
tags)
Load a single file
loadjs('/path/to/foo.js', function() {
/* foo.js loaded */
});
Fetch files in parallel and load them asynchronously
loadjs(['/path/to/foo.js', '/path/to/bar.js'], function() {
/* foo.js and bar.js loaded */
});
Fetch JavaScript and CSS files
loadjs(['/path/to/foo.css', '/path/to/bar.js'], function() {
/* foo.css and bar.js loaded */
});
Force treat file as CSS stylesheet
loadjs(['css!/path/to/cssfile.custom'], function() {
/* cssfile.custom loaded as stylesheet */
});
Add a bundle id
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar', function() {
/* foo.js & bar.js loaded */
});
Use .ready() to define bundles and callbacks separately
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar');
loadjs.ready('foobar', function() {
/* foo.js & bar.js loaded */
});
Use multiple bundles in .ready() dependency lists
loadjs('/path/to/foo.js', 'foo');
loadjs(['/path/to/bar1.js', '/path/to/bar2.js'], 'bar');
loadjs.ready(['foo', 'bar'], function() {
/* foo.js & bar1.js & bar2.js loaded */
});
Chain .ready() together
loadjs('/path/to/foo.js', 'foo');
loadjs('/path/to/bar.js', 'bar');
loadjs
.ready('foo', function() {
/* foo.js loaded */
})
.ready('bar', function() {
/* bar.js loaded */
});
Check if bundle has already been defined
if (!loadjs.isDefined('foobar')) {
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar', function() {
/* foo.js & bar.js loaded */
});
}
Fetch files in parallel and load them in series
loadjs(['/path/to/foo.js', '/path/to/bar.js'], {
success: function() { /* foo.js and bar.js loaded in series */ },
async: false
});
Add an error callback
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar', {
success: function() { /* foo.js & bar.js loaded */ },
error: function(pathsNotFound) { /* at least one path didn't load */ }
});
Retry files before calling the error callback
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar', {
success: function() { /* foo.js & bar.js loaded */ },
error: function(pathsNotFound) { /* at least one path didn't load */ },
numRetries: 3
});
Execute a callback before script tags are embedded
loadjs(['/path/to/foo.js', '/path/to/bar.js'], {
success: function() {},
error: function(pathsNotFound) {},
before: function(path, scriptEl) {
/* called for each script node before being embedded */
if (path === '/path/to/foo.js') scriptEl.crossOrigin = true;
}
});
Bypass LoadJS default DOM insertion mechanism (DOM <head>
)
loadjs(['/path/to/foo.js'], {
success: function() {},
error: function(pathsNotFound) {},
before: function(path, scriptEl) {
document.body.appendChild(scriptEl);
/* return `false` to bypass default DOM insertion mechanism */
return false;
}
});
Use bundle ids in error callback
loadjs('/path/to/foo.js', 'foo');
loadjs('/path/to/bar.js', 'bar');
loadjs(['/path/to/thunkor.js', '/path/to/thunky.js'], 'thunk');
// wait for multiple depdendencies
loadjs.ready(['foo', 'bar', 'thunk'], {
success: function() {
// foo.js & bar.js & thunkor.js & thunky.js loaded
},
error: function(depsNotFound) {
if (depsNotFound.indexOf('foo') > -1) {}; // foo failed
if (depsNotFound.indexOf('bar') > -1) {}; // bar failed
if (depsNotFound.indexOf('thunk') > -1) {}; // thunk failed
}
});
Use .done() for more control
loadjs.ready(['dependency1', 'dependency2'], function() {
/* run code after dependencies have been met */
});
function fn1() {
loadjs.done('dependency1');
}
function fn2() {
loadjs.done('dependency2');
}
Reset dependency trackers
loadjs.reset();
loadjs/ âââ dist â  âââ loadjs.js â  âââ loadjs.min.js â  âââ loadjs.umd.js âââ examples âââ gulpfile.js âââ LICENSE.txt âââ package.json âââ README.md âââ src â  âââ loadjs.js âââ test âââ umd-templates
Install dependencies
Clone repository
$ git clone git@github.com:muicss/loadjs.git
$ cd loadjs
Install node dependencies using npm
$ npm install
Build examples
$ npm run build-examples
To view the examples you can use any static file server. To use the nodejs
http-server module:
$ npm install http-server
$ npm run http-server -- -p 3000
Then visit http://localhost:3000/examples
Build distribution files
$ npm run build-dist
The files will be located in the dist
directory.
Run tests
To run the browser tests first build the loadjs
library:
$ npm run build-tests
Then visit http://localhost:3000/test
Build all files
$ npm run build-all
FAQs
Tiny async loader for modern browsers
The npm package loadjs receives a total of 183,185 weekly downloads. As such, loadjs popularity was classified as popular.
We found that loadjs demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
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