Table of contents
- 1. 요약
- 2. Created by
- 3. Description
- 4. Properties
- 5. Methods
- 6. Examples
- 7. See also
Created by
As all other objects, Function objects can be created using the new statement:
new Function ([arg1[, arg2[, ... argN]],] functionBody)
-
arg1, arg2, ... argN - Names to be used by the function as formal argument names. Each must be a string that corresponds to a valid JavaScript identifier or a list of such strings separated with a comma; for example "
x", "theValue", or "a,b".
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functionBody - A string containing the JavaScript statements comprising the function definition.
Invoking the Function constructor as a function (without using the new operator) has the same effect as invoking it as a constructor.
Description
General
Function objects created with the Function constructor are evaluated each time they are used. This is less efficient than declaring a function and calling it within your code, because declared functions are parsed only once.
Specifying arguments with the Function constructor
The following code creates a Function object that takes two arguments.
var multiply = new Function("x", "y", "return x * y")
The arguments "x" and "y" are formal argument names that are used in the function body, "return x * y".
The preceding code assigns a function to the variable multiply. To call the Function object, you can specify the variable name as if it were a function, as shown in the following examples.
var theAnswer = multiply(7, 6); var myAge = 50; if (myAge >= 39) myAge = multiply(myAge, .5);
Properties
arguments Deprecated
: An array corresponding to the arguments passed to a function. This is deprecated as property of Function, use the arguments object available within the function instead.
arity Deprecated : Specifies the number of arguments expected by the function. Use the length property instead.
caller: Specifies the function that invoked the currently executing function (non-standard).
constructor: Specifies the function that creates an object's prototype.
length: Specifies the number of arguments expected by the function.
name: The name of the function (not part of the standard).
prototype: 함수를 이용해서 만든 모든 개체에 새로운 속성을 추가할 수 있게 합니다.
Methods
apply: Allows you to apply the method of another object in the context of a different object (the calling object).
call: Allows you to call (execute) a method of another object in the context of a different object (the calling object).
toSource: Returns a string representing the source code of the function. Overrides the Object.toSource method.
toString: Returns a string representing the source code of the function. Overrides the Object.toString method.
valueOf: Returns a string representing the source code of the function. Overrides the Object.valueOf method.
Examples
Example: Creating "focus" and "blur" event handlers for a frame
The following example creates onFocus and onBlur event handlers for a frame. This code exists in the same file that contains the frameset tag. Note that scripting is the only way to create "focus" and "blur" event handlers for a frame, because you cannot specify the event handlers in the frame tag.
var frame = frames[0];
frame.onfocus = new Function("document.body.style.backgroundColor = 'white';");
frame.onblur = new Function("document.body.style.backgroundColor = '#bbbbbb';");
Page last modified 05:42, 22 Dec 2006 by Wafe