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## Sencha Documentation

# Ext.Function

A collection of useful static methods to deal with function callbacks

Defined By

### Methods

Ext.Function
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alias( Object/Function object, String methodName) : Function
Create an alias to the provided method property with name methodName of object. Note that the execution scope will st...

Create an alias to the provided method property with name `methodName` of `object`. Note that the execution scope will still be bound to the provided `object` itself.

### Parameters

- object : Object/Function
- methodName : String

### Returns

- Function

  aliasFn

Ext.Function
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bind( Function fn, [Object scope], [Array args], [Boolean/Number appendArgs]) : Function
Create a new function from the provided fn, change this to the provided scope, optionally overrides arguments for the...

Create a new function from the provided `fn`, change `this` to the provided scope, optionally overrides arguments for the call. (Defaults to the arguments passed by the caller)

### Parameters

- fn : Function

  The function to delegate.

- scope : Object

  (optional) The scope (`this` reference) in which the function is executed. If omitted, defaults to the browser window.

- args : Array

  (optional) Overrides arguments for the call. (Defaults to the arguments passed by the caller)

- appendArgs : Boolean/Number

  (optional) if True args are appended to call args instead of overriding, if a number the args are inserted at the specified position

### Returns

- Function

  The new function

Ext.Function
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createBuffered( Function fn, Number buffer, [Object scope], [Array args]) : Function
Creates a delegate function, optionally with a bound scope which, when called, buffers the execution of the passed fu...

Creates a delegate function, optionally with a bound scope which, when called, buffers the execution of the passed function for the configured number of milliseconds. If called again within that period, the impending invocation will be canceled, and the timeout period will begin again.

### Parameters

- fn : Function

  The function to invoke on a buffered timer.

- buffer : Number

  The number of milliseconds by which to buffer the invocation of the function.

- scope : Object

  (optional) The scope (`this` reference) in which the passed function is executed. If omitted, defaults to the scope specified by the caller.

- args : Array

  (optional) Override arguments for the call. Defaults to the arguments passed by the caller.

### Returns

- Function

  A function which invokes the passed function after buffering for the specified time.

Ext.Function
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createDelayed( Function fn, Number delay, [Object scope], [Array args], [Boolean/Number appendArgs]) : Function

Creates a delegate (callback) which, when called, executes after a specific delay.

Creates a delegate (callback) which, when called, executes after a specific delay.

### Parameters

- fn : Function

  The function which will be called on a delay when the returned function is called. Optionally, a replacement (or additional) argument list may be specified.

- delay : Number

  The number of milliseconds to defer execution by whenever called.

- scope : Object

  (optional) The scope (`this` reference) used by the function at execution time.

- args : Array

  (optional) Override arguments for the call. (Defaults to the arguments passed by the caller)

- appendArgs : Boolean/Number

  (optional) if True args are appended to call args instead of overriding, if a number the args are inserted at the specified position.

### Returns

- Function

  A function which, when called, executes the original function after the specified delay.

Ext.Function
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createInterceptor( Function origFn, Function newFn, [Object scope], [Mixed returnValue]) : Function
Creates an interceptor function. The passed function is called before the original one. If it returns false, the orig...

Creates an interceptor function. The passed function is called before the original one. If it returns false, the original one is not called. The resulting function returns the results of the original function. The passed function is called with the parameters of the original function. Example usage:

    var sayHi = function(name){
        alert('Hi, ' + name);
    }

    sayHi('Fred'); // alerts "Hi, Fred"

    // create a new function that validates input without
    // directly modifying the original function:
    var sayHiToFriend = Ext.Function.createInterceptor(sayHi, function(name){
        return name == 'Brian';
    });

    sayHiToFriend('Fred');  // no alert
    sayHiToFriend('Brian'); // alerts "Hi, Brian"

### Parameters

- origFn : Function

  The original function.

- newFn : Function

  The function to call before the original

- scope : Object

  (optional) The scope (`this` reference) in which the passed function is executed. If omitted, defaults to the scope in which the original function is called or the browser window.

- returnValue : Mixed

  (optional) The value to return if the passed function return false (defaults to null).

### Returns

- Function

  The new function

Ext.Function
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createSequence( Function origFn, Function newFn, [Object scope]) : Function
Create a combined function call sequence of the original function + the passed function. The resulting function retur...

Create a combined function call sequence of the original function + the passed function. The resulting function returns the results of the original function. The passed function is called with the parameters of the original function. Example usage:

    var sayHi = function(name){
        alert('Hi, ' + name);
    }

    sayHi('Fred'); // alerts "Hi, Fred"

    var sayGoodbye = Ext.Function.createSequence(sayHi, function(name){
        alert('Bye, ' + name);
    });

    sayGoodbye('Fred'); // both alerts show

### Parameters

- origFn : Function

  The original function.

- newFn : Function

  The function to sequence

- scope : Object

  (optional) The scope (this reference) in which the passed function is executed. If omitted, defaults to the scope in which the original function is called or the browser window.

### Returns

- Function

  The new function

Ext.Function
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createThrottled( Object fn, Object interval, [Object scope]) : Function
Creates a throttled version of the passed function which, when called repeatedly and rapidly, invokes the passed func...

Creates a throttled version of the passed function which, when called repeatedly and rapidly, invokes the passed function only after a certain interval has elapsed since the previous invocation.

This is useful for wrapping functions which may be called repeatedly, such as a handler of a mouse move event when the processing is expensive.

### Parameters

- fn : Object

  {Function} The function to execute at a regular time interval.

- interval : Object

  {Number} The interval in milliseconds on which the passed function is executed.

- scope : Object

  (optional) The scope (`this` reference) in which the passed function is executed. If omitted, defaults to the scope specified by the caller.

### Returns

- Function

  A function which invokes the passed function at the specified interval.

Ext.Function
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defer( Function fn, Number millis, [Object scope], [Array args], [Boolean/Number appendArgs]) : Number
Calls this function after the number of millseconds specified, optionally in a specific scope. Example usage: var sa...

Calls this function after the number of millseconds specified, optionally in a specific scope. Example usage:

    var sayHi = function(name){
        alert('Hi, ' + name);
    }

    // executes immediately:
    sayHi('Fred');

    // executes after 2 seconds:
    Ext.Function.defer(sayHi, 2000, this, ['Fred']);

    // this syntax is sometimes useful for deferring
    // execution of an anonymous function:
    Ext.Function.defer(function(){
        alert('Anonymous');
    }, 100);

### Parameters

- fn : Function

  The function to defer.

- millis : Number

  The number of milliseconds for the setTimeout call (if less than or equal to 0 the function is executed immediately)

- scope : Object

  (optional) The scope (`this` reference) in which the function is executed. If omitted, defaults to the browser window.

- args : Array

  (optional) Overrides arguments for the call. (Defaults to the arguments passed by the caller)

- appendArgs : Boolean/Number

  (optional) if True args are appended to call args instead of overriding, if a number the args are inserted at the specified position

### Returns

- Number

  The timeout id that can be used with clearTimeout

Ext.Function
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flexSetter( Function setter) : Function
A very commonly used method throughout the framework. It acts as a wrapper around another method which originally acc...

A very commonly used method throughout the framework. It acts as a wrapper around another method which originally accepts 2 arguments for `name` and `value`. The wrapped function then allows "flexible" value setting of either:

- `name` and `value` as 2 arguments
- one single object argument with multiple key - value pairs

For example:

    var setValue = Ext.Function.flexSetter(function(name, value) {
        this[name] = value;
    });

    // Afterwards
    // Setting a single name - value
    setValue('name1', 'value1');

    // Settings multiple name - value pairs
    setValue({
        name1: 'value1',
        name2: 'value2',
        name3: 'value3'
    });

### Parameters

- setter : Function

### Returns

- Function

  flexSetter

Ext.Function
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pass( Function fn, Array args, [Object scope]) : Function
Create a new function from the provided fn, the arguments of which are pre-set to args. New arguments passed to the n...

Create a new function from the provided `fn`, the arguments of which are pre-set to `args`. New arguments passed to the newly created callback when it's invoked are appended after the pre-set ones. This is especially useful when creating callbacks. For example:

    var originalFunction = function(){
        alert(Ext.Array.from(arguments).join(' '));
    };

    var callback = Ext.Function.pass(originalFunction, ['Hello', 'World']);

    callback(); // alerts 'Hello World'
    callback('by Me'); // alerts 'Hello World by Me'

### Parameters

- fn : Function

  The original function

- args : Array

  The arguments to pass to new callback

- scope : Object

  (optional) The scope (`this` reference) in which the function is executed.

### Returns

- Function

  The new callback function