Built-in Objects | Object-Oriented JavaScript

Function

JavaScript functions are objects. They can be defined using the Function constructor, like so:

>>> var sum = new Function('a', 'b', 'return a + b;');

This is equivalent to the function literal:

>>> var sum = function(a, b){return a + b;};

or the more common:

>>> function sum(a, b){return a + b;}

The use of the Function constructor is discouraged in favor of the function literals.

Members of the Function Objects

Property/Method	Description
`apply(this_obj, params_array)`	Allows you to call another function while overwriting its `this` value. The first parameter that `apply()` accepts is the object to be bound to `this` inside the function and the second is an array of parameters to be passed to the function being called. function whatIsIt(){ return this.toString(); } >>> var myObj = {}; >>> whatIsIt.apply(myObj); "[object Object]" >>> whatIsIt.apply(window); "[object Window]"
`call(this_obj, p1, p2, p3, ...)`	Same as `apply()` but accepts parameters one by one, as opposed to as one array.
`length`	The number of parameters the function expects. >>> alert.length 1 >>> parseInt.length 2

Property/Method

Description

apply(this_obj, params_array)

Allows you to call another function while overwriting its this value. The first parameter that apply() accepts is the object to be bound to this inside the function and the second is an array of parameters to be passed to the function being called.

function whatIsIt(){
  return this.toString();
}
>>> var myObj = {};
>>> whatIsIt.apply(myObj);

"[object Object]"

>>> whatIsIt.apply(window);

"[object Window]"

call(this_obj, p1, p2, p3, ...)

Same as apply() but accepts parameters one by one, as opposed to as one array.

length

The number of parameters the function expects.

>>> alert.length

>>> parseInt.length

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Object-Oriented JavaScript

Object-Oriented JavaScript

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Function

Members of the Function Objects

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