js-dependencies-loader
v4.2.2
Tiny async loader for modern browsers
0/weekUpdated 1 years agoMITUnpacked: 34.0 KB
Published by alanlang
npm install js-dependencies-loaderLoadJS
LoadJS is a tiny async loader for modern browsers (899 bytes).
Introduction
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, CSS and image 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 899 bytes (minified + gzipped).
Here's an example of what you can do with LoadJS:
``html`
You can also use more advanced syntax for more options:
`html`
The latest version of LoadJS can be found in the dist/ directory in this repository:
* https://cdn.rawgit.com/muicss/loadjs/4.2.0/dist/loadjs.js (for development)
* https://cdn.rawgit.com/muicss/loadjs/4.2.0/dist/loadjs.min.js (for production)
It's also available from these public CDNs:
* UNPKG
* https://unpkg.com/loadjs@4.2.0/dist/loadjs.js (for development)
* https://unpkg.com/loadjs@4.2.0/dist/loadjs.min.js (for production)
* CDNJS
* https://cdnjs.cloudflare.com/ajax/libs/loadjs/4.2.0/loadjs.js (for development)
* https://cdnjs.cloudflare.com/ajax/libs/loadjs/4.2.0/loadjs.min.js (for production)
You can also use it as a CJS or AMD module:
`bash`
$ npm install --save loadjs
`javascript
var loadjs = require('loadjs');
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar');
loadjs.ready('foobar', function() {
/ foo.js & bar.js loaded /
});
`
Browser Support
* IE9+ (async: false support only works in IE10+)
* Opera 12+
* Safari 5+
* Chrome
* Firefox
* iOS 6+
* Android 4.4+
LoadJS also detects script load failures from AdBlock Plus and Ghostery in:
* Safari
* Chrome
Note: LoadJS treats empty CSS files as load failures in IE9-11 and uses rel="preload" to load CSS files in Edge (to get around lack of support for onerror events on tags)
Documentation
1. Load a single file
`javascript`
loadjs('/path/to/foo.js', function() {
/ foo.js loaded /
});
1. Fetch files in parallel and load them asynchronously
`javascript`
loadjs(['/path/to/foo.js', '/path/to/bar.js'], function() {
/ foo.js and bar.js loaded /
});
1. Fetch JavaScript, CSS and image files
`javascript`
loadjs(['/path/to/foo.css', '/path/to/bar.png', 'path/to/thunk.js'], function() {
/ foo.css, bar.png and thunk.js loaded /
});
1. Force treat file as CSS stylesheet
`javascript`
loadjs(['css!/path/to/cssfile.custom'], function() {
/ cssfile.custom loaded as stylesheet /
});
1. Force treat file as image
`javascript`
loadjs(['img!/path/to/image.custom'], function() {
/ image.custom loaded /
});
1. Add a bundle id
`javascript`
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar', function() {
/ foo.js & bar.js loaded /
});
1. Use .ready() to define bundles and callbacks separately
`javascript
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar');
loadjs.ready('foobar', function() {
/ foo.js & bar.js loaded /
});
`
1. Use multiple bundles in .ready() dependency lists
`javascript
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 /
});
`
1. Chain .ready() together
`javascript
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 /
});
`
1. Use Promises to register callbacks
`javascript`
loadjs(['/path/to/foo.js', '/path/to/bar.js'], {returnPromise: true})
.then(function() { / foo.js & bar.js loaded / })
.catch(function(pathsNotFound) { / at least one didn't load / });
1. Check if bundle has already been defined
`javascript`
if (!loadjs.isDefined('foobar')) {
loadjs(['/path/to/foo.js', '/path/to/bar.js'], 'foobar', function() {
/ foo.js & bar.js loaded /
});
}
1. Fetch files in parallel and load them in series
`javascript`
loadjs(['/path/to/foo.js', '/path/to/bar.js'], {
success: function() { / foo.js and bar.js loaded in series / },
async: false
});
1. Add an error callback
`javascript`
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 / }
});
1. Retry files before calling the error callback
`javascriptnumRetries
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
});
// NOTE: Using with async: false can cause files to load out-of-sync on retries`
1. Execute a callback before script tags are embedded
`javascript`
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;
}
});
1. Bypass LoadJS default DOM insertion mechanism (DOM
)
`javascript
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;
}
});
`1. Use bundle ids in error callback
javascript
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
}
});
`
1. Use .done() for more control
javascript
loadjs.ready(['dependency1', 'dependency2'], function() {
/ run code after dependencies have been met /
}); function fn1() {
loadjs.done('dependency1');
}
function fn2() {
loadjs.done('dependency2');
}
`1. Reset dependency trackers
javascript
loadjs.reset();
`1. Implement a require-like dependency manager
javascript
var bundles = {
'bundleA': ['/file1.js', '/file2.js'],
'bundleB': ['/file3.js', '/file4.js']
}; function require(bundleIds, callbackFn) {
bundleIds.forEach(function(bundleId) {
if (!loadjs.isDefined(bundleId)) loadjs(bundles[bundleId], bundleId);
});
loadjs.ready(bundleIds, callbackFn);
}
require(['bundleA'], function() { / bundleA loaded / });
require(['bundleB'], function() { / bundleB loaded / });
require(['bundleA', 'bundleB'], function() { / bundleA and bundleB loaded / });
`Directory structure
loadjs/
├── dist
│ ├── loadjs.js
│ ├── loadjs.min.js
│ └── loadjs.umd.js
├── examples
├── gulpfile.js
├── LICENSE.txt
├── package.json
├── README.md
├── src
│ └── loadjs.js
├── test
└── umd-templates
Development Quickstart
1. Install dependencies
* nodejs
* npm
* http-server (via npm)
1. Clone repository
bash
$ git clone git@github.com:muicss/loadjs.git
$ cd loadjs
`1. Install node dependencies using npm
bash
$ npm install
`1. Build examples
bash
$ npm run build-examples
` To view the examples you can use any static file server. To use the
http-server module:
`bash
$ npm install http-server
$ npm run http-server -- -p 3000
` Then visit http://localhost:3000/examples
1. Build distribution files
bash
$ npm run build-dist
` The files will be located in the
directory.1. Run tests
To run the browser tests first build the
loadjs library:
`bash
$ npm run build-tests
` Then visit http://localhost:3000/test
1. Build all files
bash
$ npm run build-all
``