ExtReact Docs Help


The documentation for the ExtReact product diverges somewhat from the documentation of other Sencha products. The sections below describe documentation for all products except where indicated as unique to ExtReact.

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.

ExtReact component classes list the configurable name prominently at the top of the API class doc followed by the fully-qualified class name.

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

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.


item :  Object

The config object being added.


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

Or in the case of an ExtReact component class this indicates a member of type prop

- 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.

ExtReact component classes do not hoist the getter / setter methods into the prop. All methods will be described in the Methods section

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, inheritance, and read only. 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.

ExtWebComponents 7.1.0


Ext.util.Cache private

NPM Package



NOTE: This is a private utility class for internal use by the framework. Don't rely on its existence.


This class is used to manage simple, LRU caches. It provides an absolutely minimal container interface. It is created like this:

 this.itemCache = new Ext.util.Cache({
     miss: function (key) {
         return new CacheItem(key);

The miss abstract method must be implemented by either a derived class or at the instance level as shown above.

Once the cache exists and it can handle cache misses, the cache is used like so:

 var item = this.itemCache.get(key);

The key is some value that uniquely identifies the cached item.

In some cases, creating the cache item may require more than just the lookup key. In that case, any extra arguments passed to get will be passed to miss.

 this.otherCache = new Ext.util.Cache({
     miss: function (key, extra) {
         return new CacheItem(key, extra);

 var item = this.otherCache.get(key, extra);

To process items as they are removed, you can provide an evict method. The stock method is Ext.emptyFn and so does nothing.

For example:

 this.itemCache = new Ext.util.Cache({
     miss: function (key) {
         return new CacheItem(key);

     evict: function (key, cacheItem) {
No members found using the current filters


Optional Configs

maxSize : Number

The maximum size the cache is allowed to grow to before further additions cause removal of the least recently used entry.

Defaults to:




Instance Methods


Removes all items from this cache.

evict ( key, value )
template tpl protected pro

This method is called internally from get when the cache is full and the least-recently-used (LRU) item has been removed.


key :  String

The cache lookup key for the item being removed.

value :  Object

The cache value (returned by miss) for the item being removed.

This is a template method. a hook into the functionality of this class. Feel free to override it in child classes.

get ( key, args ) : Object

Finds an item in this cache and returns its value. If the item is present, it is shuffled into the MRU (most-recently-used) position as necessary. If the item is missing, the miss method is called to create the item.


key :  String

The cache key of the item.

args :  Object...

Arguments for the miss method should it be needed.



The cached object.

miss ( key, args )
abstract abs protected pro

This method is called by get when the key is not found in the cache. The implementation of this method should create the (expensive) value and return it. Whatever arguments were passed to get will be passed on to this method.


key :  String

The cache lookup key for the item.

args :  Object...

Any other arguments originally passed to get.

ExtWebComponents 7.1.0