l.js: Load CSS and JavaScript files in parallel

# l.js is another simple/tiny javascript/css loader
[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fmalko%2Fl.js.svg?type=shield)](https://app.fossa.io/projects/git%2Bgithub.com%2Fmalko%2Fl.js?ref=badge_shield)


## features
- compatible with all ECMASCRIPT 5.1 browsers (Warning for old users this is a breaking change on supporting long time deprecated browsers)
- parallel script / css loading
- callback after script loading (css support callback too but are executed imediately)
- tiny only 2ko uglifyed, less than 1.1ko gziped (at least for latest revision)
- may load in order to preserve dependencies
- support aliases for simpler calling
- on demand loading
- only one script tag required
- clear syntax (to use not in the source code :) )
- successive load of same file will load it once but execute all callbacks associated
- can dumbly check already inserted tags at load time
- may use a fallback url on error (only for js files and with error events compatible browsers)
- may register error handlers (only for js files and with error events compatible browsers)
- can load javascripts modules

## examples

### loading ljs and another libs with one single tag
```html
<script src="l.js">
	ljs.load('myLib.js',function(){ /* your callback here */});
</script>
```
or using jsdeliver CDN:
```html
<script src="https://cdn.jsdelivr.net/gh/malko/l.js@latest/l.min.js">
	ljs.load('myLib.js',function(){ /* your callback here */});
</script>
```

> If you're looking for the npm package, you should search for **@malko/l.js**
> ```npm install @malko/l.js```

### loading some scripts in parallel others in order
```html
<script src="l.js">
	ljs
		.load('myLib.js')
		.load('myRequiredLib.js','myDependentLib.js',function(){ /* your callback here */})
	;
</script>
```
second load will be executed in parallel of first load but myDependentLib.js won't load before myRequireLib.js is loaded

```html
<script src="l.js">
	ljs.load(['myLib.js','myRequiredLib.js'],'myDependentLib.js',function(){ /* your callback here */});
</script>
```
this will load myLib.js and myRequiredLib.js in parrallel and wait for them before loading myDependentLib.js


### using some aliases for simpler loading
```html
<script src="l.js?checkLoaded"> // <- adding checkLoaded to the url will dumbly check already inserted script/link tags
	ljs
		.addAliases({
			jQuery:'http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js#jqueryId' // <- script tag will have attribute id=jqueryId
			,ui:[
				'jQuery'
				,'https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.18/jquery-ui.min.js'
				,'myUITheme.css'
			]
		})
		.load('ui',function(){
			/* work with both jquery and jquery-ui here */
		})
	;
</script>
```

### define a fallback url
l.js also support a fallback url for javascript files in case you want to try to get the resource from another location on loading failure
You can define this fallback url parameter like you define ids. The difference is you will prefix with **#=** instead of # alone
```html
<script src="l.js">
	ljs.load('http://domain.com/myLib.js#=/myfallback.js#myid',function(){
		/*
			generated script tag will have myid as id and will try to load /myfallback.js if it fail to load http://domain.com/myLib.js
		*/
	});
</script>
```

### register an error handler
```html
<script src="l.js">
	ljs
		.load('missingFile.js',function(){ /* your callback here */})
		.onError(function(url) {
			console.log('error loading', url); // <- will print "error loading missingFile.js"
		})
	;
</script>
```

### load a js module
As a default l.js load js scripts with their type attribute set to `text/javascript`. To set type to `module` instead, simply prefix the url with `module:`

```html
<script src="l.js">
    ljs.load('module:myModuleLib.js',function(){ /* your callback here */});
</script>
```

this piece of code is dual licensed under MIT / GPL
Hope this help, code review, suggestions, bug reports are welcome and appreciated.


## License
[![FOSSA Status](https://app.fossa.io/api/projects/git%2Bgithub.com%2Fmalko%2Fl.js.svg?type=large)](https://app.fossa.io/projects/git%2Bgithub.com%2Fmalko%2Fl.js?ref=badge_large)