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Terms, Icons, and Labels

Many classes have shortcut names used when creating (instantiating) a class with a configuration object. The shortcut name is referred to as an alias (or xtype if the class extends Ext.Component). The alias/xtype is listed next to the class name of applicable classes for quick reference.

Access Levels

Framework classes or their members may be specified as private or protected. Else, the class / member is public. Public, protected, and private are access descriptors used to convey how and when the class or class member should be used.

Member Types

Member Syntax

Below is an example class member that we can disect to show the syntax of a class member (the lookupComponent method as viewed from the Ext.button.Button class in this case).

lookupComponent ( item ) : Ext.Component
protected

Called when a raw config object is added to this container either during initialization of the items config, or when new items are added), or {@link #insert inserted.

This method converts the passed object into an instanced child component.

This may be overridden in subclasses when special processing needs to be applied to child creation.

Parameters

item :  Object

The config object being added.

Returns
Ext.Component

The component to be added.

Let's look at each part of the member row:

Member Flags

The API documentation uses a number of flags to further commnicate the class member's function and intent. The label may be represented by a text label, an abbreviation, or an icon.

Class Icons

- Indicates a framework class

- A singleton framework class. *See the singleton flag for more information

- A component-type framework class (any class within the Ext JS framework that extends Ext.Component)

- Indicates that the class, member, or guide is new in the currently viewed version

Member Icons

- Indicates a class member of type config

- Indicates a class member of type property

- Indicates a class member of type method

- Indicates a class member of type event

- Indicates a class member of type theme variable

- Indicates a class member of type theme mixin

- Indicates that the class, member, or guide is new in the currently viewed version

Class Member Quick-Nav Menu

Just below the class name on an API doc page is a row of buttons corresponding to the types of members owned by the current class. Each button shows a count of members by type (this count is updated as filters are applied). Clicking the button will navigate you to that member section. Hovering over the member-type button will reveal a popup menu of all members of that type for quick navigation.

Getter and Setter Methods

Getting and setter methods that correlate to a class config option will show up in the methods section as well as in the configs section of both the API doc and the member-type menus just beneath the config they work with. The getter and setter method documentation will be found in the config row for easy reference.

History Bar

Your page history is kept in localstorage and displayed (using the available real estate) just below the top title bar. By default, the only search results shown are the pages matching the product / version you're currently viewing. You can expand what is displayed by clicking on the button on the right-hand side of the history bar and choosing the "All" radio option. This will show all recent pages in the history bar for all products / versions.

Within the history config menu you will also see a listing of your recent page visits. The results are filtered by the "Current Product / Version" and "All" radio options. Clicking on the button will clear the history bar as well as the history kept in local storage.

If "All" is selected in the history config menu the checkbox option for "Show product details in the history bar" will be enabled. When checked, the product/version for each historic page will show alongside the page name in the history bar. Hovering the cursor over the page names in the history bar will also show the product/version as a tooltip.

Search and Filters

Both API docs and guides can be searched for using the search field at the top of the page.

On API doc pages there is also a filter input field that filters the member rows using the filter string. In addition to filtering by string you can filter the class members by access level and inheritance. This is done using the checkboxes at the top of the page.

The checkbox at the bottom of the API class navigation tree filters the class list to include or exclude private classes.

Clicking on an empty search field will show your last 10 searches for quick navigation.

API Doc Class Metadata

Each API doc page (with the exception of Javascript primitives pages) has a menu view of metadata relating to that class. This metadata view will have one or more of the following:

Expanding and Collapsing Examples and Class Members

Runnable examples (Fiddles) are expanded on a page by default. You can collapse and expand example code blocks individually using the arrow on the top-left of the code block. You can also toggle the collapse state of all examples using the toggle button on the top-right of the page. The toggle-all state will be remembered between page loads.

Class members are collapsed on a page by default. You can expand and collapse members using the arrow icon on the left of the member row or globally using the expand / collapse all toggle button top-right.

Desktop -vs- Mobile View

Viewing the docs on narrower screens or browsers will result in a view optimized for a smaller form factor. The primary differences between the desktop and "mobile" view are:

Viewing the Class Source

The class source can be viewed by clicking on the class name at the top of an API doc page. The source for class members can be viewed by clicking on the "view source" link on the right-hand side of the member row.

Sencha Cmd 6.x

Guides
API
top

Compiler-Friendly Code Guidelines

One of the major components in Sencha Cmd is its compiler. This guide describes how to write code that gets the most out of the compiler and prepares for future framework-aware optimizations.

Prerequisites

The following guides are recommended reading before proceeding further:

What The Compiler Is Not

Sencha Cmd compiler is not a replacement for tools like these:

These tools solve different problems for JavaScript developers and are very good at the world of JavaScript, but have no understanding of Sencha framework features such as Ext.define for declaring classes.

Framework Awareness

The role of the Sencha Cmd compiler is to provide framework-aware optimizations and diagnostics. Once code has passed through the Sencha Cmd compiler, it is ready for more general tools.

These kinds of optimizations have shown to significantly improve the "ingest" time of JavaScript code by the browser, especially on legacy browsers.

For the compiler to provide these benefits, however, it is now important to look at the coding conventions that the compiler can "understand" and therefore optimize for you. Following the conventions described in this guide ensure that your code is positioned to get the most from Sencha Cmd today and in the future.

Code Organization

The dynamic loader and the previous JSBuilder have always made certain assumptions about how classes are organized, but they were not seriously impacted by failure to follow those guidelines. These guidelines are very similar to Java.

To recap, these guidelines are:

  • Each JavaScript source file should contain one Ext.define statement at global scope.
  • The name of a source file matches the last segment of the name of the defined type such as the name of the source file containing Ext.define("MyApp.foo.bar.Thing", ... is "Thing.js".
  • All source files are stored in a folder structure that is based on the namespace of the defined type. For example, given Ext.define("MyApp.foo.bar.Thing", ..., the source file is in a path ending with "/foo/bar".

Internally, the compiler views source files and classes as basically synonymous. It makes no attempt to split up files to remove classes that are not required. Only complete files are selected and included in the output. This means that if any class in a source file is required, all classes in the file will be included in the output.

To give the compiler the freedom to select code at the class-level, it is essential to put only one class in each file.

Class Declaration

The Sencha Class System provides the Ext.define function to enable high-level, object oriented programming. The compiler takes the view that Ext.define is really a form of "declarative" programming and processes the "class declaration" accordingly.

Clearly if Ext.define is understood as a declaration, the content of the class body cannot be constructed dynamically in code. While this practice is rare, it is valid JavaScript. But as we shall see below in the code forms, this is antithetical to the compiler's ability to understand the code it parses. Dynamic class declarations are often used to do things that are better handled by other features of the compiler. For more on these features, see the Sencha Compiler Reference.

The compiler understands these "keywords" of this declarative language:

  • requires
  • uses
  • extend
  • mixins
  • statics
  • alias
  • singleton
  • override
  • alternateClassName
  • xtype

For the compiler to recognize your class declarations, they need to follow one of the following forms.

Standard Form

Most classes use simple declarations like this:

Ext.define('Foo.bar.Thing', {
    // keywords go here ... such as:

    extend: '...',

    // ...
});

The second argument is the class body which is processed by the compiler as the class "declaration".

Note: In all forms, call Ext.define at global scope.

Wrapped Function Forms

In some use cases the class declaration is wrapped in a function to create a closure scope for the class methods. In all of the various forms, it is critical for the compiler that the function end with a return statement that returns the class body as an object literal. Other techniques are not recognized by the compiler.

Function Form

To streamline the older forms of this technique described below, Ext.define understands that if given a function as its second argument, that it should invoke that function to produce the class body. It also passes the reference to the class as the single argument to facilitate access to static members via the closure scope. Internally to the framework, this was the most common reason for the closure scope.

Ext.define('Foo.bar.Thing', function (Thing) {

    return {
        // keywords go here ... such as:

        extend: '...',

        // ...
    };
});

Note: This form is only supported in Ext JS 4.1.2 and later and Sencha Touch 2.1 and later.

Called Function Form

In previous releases, the "Function Form" was not supported, so the function was simply invoked immediately:

Ext.define('Foo.bar.Thing', function () {

    return {
        // keywords go here ... such as:

        extend: '...',

        // ...
    };
}());

Called-Parenthesized Function Form

This form and the next are commonly used to appease tools like JSHint (or JSLint).

Ext.define('Foo.bar.Thing', (function () {

    return {
        // keywords go here ... such as:

        extend: '...',

        // ...
    };
})());

Parenthesized-Called Function Form

Another variation on immediately called "Function Form" to appease JSHint/JSLint.

Ext.define('Foo.bar.Thing', (function () {

    return {
        // keywords go here ... such as:

        extend: '...',

        // ...
    };
}()));

Keywords

The class declaration in its many forms ultimately contains "keywords". Each keyword has its own semantics, but there are many that have a common "shape".

Keywords using String

The extend and override keywords only accept a string literal.

These keywords are also mutually exclusive in that only one can be used in any declaration.

Keywords using String or String[]

The following keywords all have the same form:

  • requires
  • uses
  • alias
  • alternateClassName
  • xtype

The supported forms for these keywords are as follows.

Just a string:

requires: 'Foo.thing.Bar',
//...

An array of strings:

requires: [ 'Foo.thing.Bar', 'Foo.other.Thing' ],
//...

Forms of mixins

Using an object literal, the name given the mixin can be quoted or not:

mixins: {
    name: 'Foo.bar.Mixin',
    'other': 'Foo.other.Mixin'
},
//...

Mixins can also be specified as a String[]:

mixins: [
    'Foo.bar.Mixin',
    'Foo.other.Mixin'
],
//...

This approach relies on the mixinId of the mixin class but also allows the receiving class to control the mixin order. This is important if the mixins have overlapping methods or properties and the receiving class wants to control which mixin supplies the overlapping methods or properties.

The statics Keyword

This keyword places properties or methods on the class, as opposed to on each of the instances. This must be an object literal.

statics: {
    // members go here
},
// ...

The singleton Keyword

This keyword was historically only used with a boolean "true" value:

singleton: true,

The following (redundant) use is also supported:

singleton: false,

Overrides

In Ext JS 4.1.0 and Sencha Touch 2.0, Ext.define gained the ability to manage overrides. Historically, overrides have been used to patch code to work around bugs or add enhancements. This use was complicated with the introduction of the dynamic loader because of the timing required to execute the Ext.override method. Also, in large applications with many overrides, not all overrides in the code base were needed by all pages or builds (for example, if the target class was not required).

All this changed once the class system and loader understood overrides. This trend only continues with Sencha Cmd. The compiler understands overrides and their dependency effects and load-sequence issues.

In the future, the compiler will become even more aggressive at dead-code elimination of methods replaced by an override. Using managed overrides as described below enables this optimization of your code once it's available in Sencha Cmd.

Standard Override Form

Below is the standard form of an override. The choice of namespace is somewhat arbitrary, but see below for suggestions.

Ext.define('MyApp.patches.grid.Panel', {
    override: 'Ext.grid.Panel',

    ...
});

Use Cases

With the ability to use Ext.define to manage overrides, new idioms have opened up and are actively being leveraged. For example in the code generators of Sencha Architect and internal to the framework, that break apart large classes like Ext.Element into more manageable and cohesive pieces.

Overrides as Patches

Overrides as patches are the historical use case and hence the most common in practice today.

Caution: Take care when patching code. While the use of override itself is supported, the end result of overriding framework methods is not supported. All overrides should be carefully reviewed whenever upgrading to a new framework version.

That said, it is, at times, necessary to override framework methods. The most common case for this to fix a bug. The Standard Override Form is ideal in this case. In fact, Sencha Support will at times provide customer with patches in this form. Once provided, however, managing such patches and removing them when no longer needed, is a matter for the review process previously mentioned.

Naming Recommendation:
  • Organize patches in a namespace associated with the top-level namespace of the target. For example, "MyApp.patches" targets the "Ext" namespace. If third party code is involved then perhaps another level or namespace should be chosen to correspond to its top-level namespace. From there, name the override using a matching name and sub-namespace. In the previous example:

    Ext -> MyApp.patches).grid.Panel

Overrides as Partial Classes

When dealing with code generation (as in Sencha Architect), it is common for a class to consist of two parts: one machine generated and one human edited. In some languages, there is formal support for the notion of a "partial class" or a class-in-two-parts.

Using an override, you can manage this cleanly:

In ./foo/bar/Thing.js:

Ext.define('Foo.bar.Thing', {
    // NOTE: This class is generated - DO NOT EDIT...

    requires: [
        'Foo.bar.custom.Thing'
    ],

    method: function () {
        // some generated method
    },

    ...
});

In ./foo/bar/custom/Thing.js:

Ext.define('Foo.bar.custom.Thing', {
    override: 'Foo.bar.Thing',

    method: function () {
        this.callParent(); // calls generated method
        ...
    },

    ...
});

Naming Recommendations:

  • Organize generated vs. hand-edited code by namespace.
  • If not by namespace, consider a common base name with a suffix on one or the other, such as Foo.bar.ThingOverride or Foo.bar.ThingGenerated so that the parts of a class collate together in listings.

Overrides as Aspects

A common problem for base classes in object-oriented designs is the "fat base class". This happens because some behaviors apply across all classes. When these behaviors (or features) are not needed, however, they cannot be readily removed if they are implemented as part of some large base class.

Using overrides, these features can be collected in their own hierarchy and then requires can be used to select these features when needed.

In ./foo/feature/Component.js:

Ext.define('Foo.feature.Component', {
    override: 'Ext.Component',

    ...
});

In ./foo/feature/grid/Panel.js:

Ext.define('Foo.feature.grid.Panel', {
    override: 'Ext.grid.Panel',

    requires: [
        'Foo.feature.Component' // since overrides do not "extend" each other
    ],

    ...
});

This feature can be used now by requiring it:

...
requires: [
    'Foo.feature.grid.Panel'
]

Or with a proper "bootstrap" file (see Workspaces in Sencha Cmd

...
requires: [
    'Foo.feature.*'
]

Naming Recommendation:

  • Organize generated vs. hand-edited code by namespace. This enables use of wildcards to bring in all aspects of the feature.

Using requires and uses in an Override

These keywords are supported in overrides. Use of requires may limit the compiler's ability to reorder the code of an override.

Using callParent and callSuper

To support all of these new uses cases, callParent was enhanced in Ext JS 4.0 and Sencha Touch 2.0 to "call the next method". The "next method" may be an overridden method or an inherited method. As long as there is a next method, callParent will call it.

Another way to view this is that callParent works the same for all forms of Ext.define, be they classes or overrides.

While this helped in some areas, it unfortunately made bypassing the original method (as a patch or bug fix) more difficult. Ext JS 4.1 and later and Sencha Touch 2.1 and later provides a method named callSuper that can bypass an overridden method.

In future releases, the compiler will use this semantic difference to perform dead-code elimination of overridden methods.

Override Compatibility

Starting in version 4.2.2, overrides can declare their compatibility based on the framework version or on versions of other packages. This can be useful for selectively applying patches that are safely ignored when they are incompatible with the target class version.

The simplest use case is to test framework version for compatibility:

Ext.define('App.overrides.grid.Panel', {
    override: 'Ext.grid.Panel',

    compatibility: '4.2.2', // only if framework version is 4.2.2

    //...
});

An array is treated as an OR, so if any specs match, the override is compatible.

Ext.define('App.overrides.some.Thing', {
    override: 'Foo.some.Thing',

    compatibility: [
        '4.2.2',
        'foo@1.0.1-1.0.2'
    ],

    //...
});

To require that all specifications match, an object can be provided:

Ext.define('App.overrides.some.Thing', {
    override: 'Foo.some.Thing',

    compatibility: {
        and: [
            '4.2.2',
            'foo@1.0.1-1.0.2'
        ]
    },

    //...
});

Because the object form is just a recursive check, these can be nested:

Ext.define('App.overrides.some.Thing', {
    override: 'Foo.some.Thing',

    compatibility: {
        and: [
            '4.2.2',  // exactly version 4.2.2 of the framework *AND*
            {
                // either (or both) of these package specs:
                or: [
                    'foo@1.0.1-1.0.2',
                    'bar@3.0+'
                ]
            }
        ]
    },

    //...
});

For details on version syntax, see the checkVersion method of Ext.Version.

Conclusion

As Sencha Cmd continues to evolve, it continues to introduce new diagnostic messages to help point out deviations from these guidelines.

A good place to start is to see how this information can help inform your own internal code style guidelines and practices.

Next Steps

Sencha Cmd 6.x

Ext JS
Sencha Test
Cmd
Sencha Themer
GXT
IDE Plugins
Sencha Inspector
Architect
Sencha Fiddle
Touch
Offline Documentation

Sencha Test

2.0.1 2.0.0 1.0.3

Cmd

Cmd

Sencha Themer

1.1.0 1.0.2

GXT

4.x 3.x

IDE Plugins

IDE Plugins

Sencha Inspector

Sencha Inspector

Sencha Fiddle

Sencha Fiddle

Offline Documentation

Offline Documentation