Ext.Loader
Files
Guide
Dependencies and MVCExt.Loader is the heart of the new dynamic dependency loading capability in Ext JS 4+. It is most commonly used via the Ext.require shorthand. Ext.Loader supports both asynchronous and synchronous loading approaches, and leverage their advantages for the best development flow. We'll discuss about the pros and cons of each approach.
Note The Loader is only enabled by default in development versions of the library (eg sencha-touch-debug.js). To
explicitly enable the loader, use Ext.Loader.setConfig({ enabled: true }); before the start of your script.
Asynchronous Loading
Advantages:
- Cross-domain
- No web server needed: you can run the application via the file system protocol (i.e:
file://path/to/your/index .html) - Best possible debugging experience: error messages come with the exact file name and line number
Disadvantages:
- Dependencies need to be specified before-hand
Method 1: Explicitly include what you need:
// Syntax
Ext.require({String/Array} expressions);
// Example: Single alias
Ext.require('widget.window');
// Example: Single class name
Ext.require('Ext.window.Window');
// Example: Multiple aliases / class names mix
Ext.require(['widget.window', 'layout.border', 'Ext.data.Connection']);
// Wildcards
Ext.require(['widget.*', 'layout.*', 'Ext.data.*']);
Method 2: Explicitly exclude what you don't need:
// Syntax: Note that it must be in this chaining format.
Ext.exclude({String/Array} expressions)
.require({String/Array} expressions);
// Include everything except Ext.data.*
Ext.exclude('Ext.data.*').require('*');
// Include all widgets except widget.checkbox*,
// which will match widget.checkbox, widget.checkboxfield, widget.checkboxgroup, etc.
Ext.exclude('widget.checkbox*').require('widget.*');
Synchronous Loading on Demand
Advantages:
- There's no need to specify dependencies before-hand, which is always the convenience of including ext-all.js before
Disadvantages:
- Not as good debugging experience since file name won't be shown (except in Firebug at the moment)
- Must be from the same domain due to XHR restriction
- Need a web server, same reason as above
There's one simple rule to follow: Instantiate everything with Ext.create instead of the new keyword
Ext.create('widget.window', { ... }); // Instead of new Ext.window.Window({...});
Ext.create('Ext.window.Window', {}); // Same as above, using full class name instead of alias
Ext.widget('window', {}); // Same as above, all you need is the traditional `xtype`
Behind the scene, Ext.ClassManager will automatically check whether the given class name / alias has already existed on the page. If it's not, Ext.Loader will immediately switch itself to synchronous mode and automatic load the given class and all its dependencies.
Hybrid Loading - The Best of Both Worlds
It has all the advantages combined from asynchronous and synchronous loading. The development flow is simple:
Step 1: Start writing your application using synchronous approach. Ext.Loader will automatically fetch all
dependencies on demand as they're needed during run-time. For example: ###
Ext.onReady(function(){
var window = Ext.createWidget('window', {
width: 500,
height: 300,
layout: {
type: 'border',
padding: 5
},
title: 'Hello Dialog',
items: [{
title: 'Navigation',
collapsible: true,
region: 'west',
width: 200,
html: 'Hello',
split: true
}, {
title: 'TabPanel',
region: 'center'
}]
});
window.show();
})
Step 2: Along the way, when you need better debugging ability, watch the console for warnings like these:
[Ext.Loader] Synchronously loading 'Ext.window.Window'; consider adding Ext.require('Ext.window.Window') before your application's code
ClassManager.js:432
[Ext.Loader] Synchronously loading 'Ext.layout.container.Border'; consider adding Ext.require('Ext.layout.container.Border') before your application's code
Simply copy and paste the suggested code above Ext.onReady, i.e:
Ext.require('Ext.window.Window');
Ext.require('Ext.layout.container.Border');
Ext.onReady(...);
Everything should now load via asynchronous mode.
Deployment
It's important to note that dynamic loading should only be used during development on your local machines. During production, all dependencies should be combined into one single JavaScript file. Ext.Loader makes the whole process of transitioning from / to between development / maintenance and production as easy as possible. Internally Ext.Loader.history maintains the list of all dependencies your application needs in the exact loading sequence. It's as simple as concatenating all files in this array into one, then include it on top of your application.
This process will be automated with Sencha Command, to be released and documented towards Ext JS 4 Final.
Available since: 2.0.0
Config options
Appends current timestamp to script files to prevent caching Defaults to true
Defaults to: true
Available since: 2.0.0
The get parameter name for the cache buster's timestamp. Defaults to '_dc'
Defaults to: '_dc'
Available since: 2.0.0
Whether or not to enable the dynamic dependency loading feature Defaults to true
Defaults to: true
Available since: 2.0.0
The mapping from namespaces to file paths {
'Ext': '.', // This is set by default, Ext.layout.container.Container will be
// loaded from ./layout/Container.js
'My': './src/my_own_folder' // My.layout.Container will be loaded from
// ./src/my_own_folder/layout/Container.js
}
Note that all relative paths are relative to the current HTML document.
If not being specified, for example, Other.awesome.Class
will simply be loaded from ./Other/awesome/Class.js
Defaults to: {'Ext': '.'}
Available since: 2.0.0
Properties
Configuration
Defaults to: {enabled: true, disableCaching: true, disableCachingParam: '_dc', paths: {'Ext': '.'}}
Available since: 2.0.0
An array of class names to keep track of the dependency loading order. This is not guaranteed to be the same everytime due to the asynchronous nature of the Loader.
Defaults to: []
Available since: 2.0.0
Maintain the list of files that have already been handled so that they never get double-loaded
Defaults to: {}
Available since: 2.0.0
Flag indicating whether there are still files being loaded
Defaults to: false
Available since: 2.0.0
Contains optional dependencies to be loaded last
Defaults to: []
Available since: 2.0.0
Maintain the queue for all dependencies. Each item in the array is an object of the format: {
requires: [...], // The required classes for this queue item
callback: function() { ... } // The function to execute when all classes specified in requires exist
}
Defaults to: []
Available since: 2.0.0
Maintain the list of listeners to execute when all required scripts are fully loaded
Defaults to: []
Available since: 2.0.0
Map of fully qualified class names to an array of dependent classes.
Defaults to: {}
Available since: 2.0.0
Methods
Explicitly exclude files from being loaded. Useful when used in conjunction with a broad include expression.
Can be chained with more require and exclude methods, eg:
Ext.exclude('Ext.data.*').require('*');
Ext.exclude('widget.button*').require('widget.*');
Available since: 2.0.0
Parameters
- excludes : Array
Returns
- Object
object contains
requiremethod for chaining
Translates a className to a file path by adding the the proper prefix and converting the .'s to /'s. For example:
Ext.Loader.setPath('My', '/path/to/My');
alert(Ext.Loader.getPath('My.awesome.Class')); // alerts '/path/to/My/awesome/Class.js'
* Note that the deeper namespace levels, if explicitly set, are always resolved first. For example:
Ext.Loader.setPath({
'My': '/path/to/lib',
'My.awesome': '/other/path/for/awesome/stuff',
'My.awesome.more': '/more/awesome/path'
});
alert(Ext.Loader.getPath('My.awesome.Class')); // alerts '/other/path/for/awesome/stuff/Class.js'
alert(Ext.Loader.getPath('My.awesome.more.Class')); // alerts '/more/awesome/path/Class.js'
alert(Ext.Loader.getPath('My.cool.Class')); // alerts '/path/to/lib/cool/Class.js'
alert(Ext.Loader.getPath('Unknown.strange.Stuff')); // alerts 'Unknown/strange/Stuff.js'
Available since: 2.0.0
Parameters
- className : String
Returns
- String
path
Add a new listener to be executed when all required scripts are fully loaded
Available since: 2.0.0
Parameters
Refresh all items in the queue. If all dependencies for an item exist during looping, it will execute the callback and call refreshQueue again. Triggers onReady when the queue is empty
Available since: 2.0.0
Returns
- Ext.Loader
this
Loads all classes by the given names and all their direct dependencies; optionally executes the given callback function when finishes, within the optional scope. This method is aliased by Ext.require for convenience
Available since: 2.0.0
Parameters
Set the configuration for the loader. This should be called right after ext-(debug).js is included in the page, and before Ext.onReady. i.e:
<script type="text/javascript" src="ext-core-debug.js"></script>
<script type="text/javascript">
Ext.Loader.setConfig({
enabled: true,
paths: {
'My': 'my_own_path'
}
});
<script>
<script type="text/javascript">
Ext.require(...);
Ext.onReady(function() {
// application code here
});
</script>
Refer to config options of Ext.Loader for the list of possible properties
Available since: 2.0.0
Parameters
- config : Object
The config object to override the default values
Returns
- Ext.Loader
this
Sets the path of a namespace. For Example:
Ext.Loader.setPath('Ext', '.');
Available since: 2.0.0
Parameters
- name : String/Object
See flexSetter
- path : String
See flexSetter
Returns
- Ext.Loader
this
Synchronously loads all classes by the given names and all their direct dependencies; optionally executes the given callback function when finishes, within the optional scope. This method is aliased by Ext.syncRequire for convenience
Available since: 2.0.0