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書名： Ext JS 3.0 Cookbook
作者名： Jorge Ramon
本章字?jǐn)?shù)： 257字
更新時(shí)間： 2021-04-01 13:43:45

Preventing naming conflicts and scoping non-global variables

Naming conflicts and scoping problems increase as applications gain size, and you start to work with multiple code files and modules. In Ext JS, you can resolve these issues by creating namespaces where you can logically organize your code.

How to do it...

The following steps will show how to create a namespace and "hide" local variables in it. These variables will not collide with similarly-named variables that are stored in other namespaces or have global scope:

Define a namespace for the variables that are not global:
```
Ext.namespace('ExtJSCookbook.Samples');
```

Create a local variable and a global variable with the same name:

Ext JSCookbook.Samples.var1 = 'var1 (local)';
// ExtJSCookbook.Samples.var1 is limited to the ExtJSCookbook.Samples namespace
var var1 = 'var1 (global)';
// var1 is a global variable

Prevent name collisions by putting any custom types inside the namespace you created:

// A custom type inside the Ext JSCookbook.Samples namespace
ExtJSCookbook.Samples.Person = function() {
return {
firstName: '',
lastName: '',
show: function() {
alert(this.firstName + ' ' + this.lastName);
}
}
}
var person1 = new Ext JSCookbook.Samples.Person();
person1.firstName = 'Jorge';
person1.lastName = 'Ramon';
person1.show();

How it works...

Ext.namespace(namespace1, namespace2, namespace3,...) and its shorthand Ext.ns(...) allow you to create an arbitrary number of namespaces that you can use to scope variables and classes that are not global. For example, have a look at the following piece of code:

Ext.namespace('MyApplication', 'MyApplication.UI', 'MyApplication.Data', 'MyApplication.Services');

This namespace's definition above is equivalent to the following statements:

MyApplication = {};
MyApplication.UI = {};
MyApplication.Data = {};
MyApplication.Services = {};

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Ext JS 3.0 Cookbook

Preventing naming conflicts and scoping non-global variables

How to do it...

How it works...