Javascript dynamic objects

Question

I don't really know the correct words to describe what I am trying to do, but the functionality is very similar to overriding the __get() function of PHP classes. For example this is what I want to do.

var obj = {
 param1:'a',
 func1:function(){ return '1';},
 catch_all:function(input){
 return input;
 }
}
//alerts 'a'
alert( obj.param1 );
//alerts '1'
alert( obj.func1() );
//alerts 'anything'
alert( obj.anything );

Basically I want a way to redirect any unused key to a predefined key. I have done some research on this and really didn't know what to search for. Any help is greatly appreciated. Thanks.

• Christian C. Salvadó: See also: stackoverflow.com/questions/2266789/…

Answer 1

This is impossible with the current JavaScript implementations. There is not any kind of default getter as you have in ObjC or other languages.

Answer 2

You can make a get function, but aside from that you cannot do what you intend.

A get function:

var obj = {
 param1:'a',
 func1:function(){ return '1';},
 get: function(input){
 return this[input] !== undefined ? this[input] : 'ERROR';
 }
}
//alerts 'a'
alert( obj.param1 );
//alerts '1'
alert( obj.func1() );
//alerts 'ERROR'
alert( obj.get('anything') );

Fiddle: http://jsfiddle.net/maniator/T2gWx/

Answer 3

Kindly find the changes in the code of get method. It is able to modify the memory value reference by obj's param1.

var obj = {
 param1:'a',
 func1:function(){ return '1';},
 get: function(input){
 this.param1 = input;
 return input;
 }
}
//alerts 'a'
alert( obj.param1 );
//alerts '1'
alert( obj.func1() );
//alerts 'anything'
alert( obj.param1 );

Answer 4

I think what you want are called harmony proxies.

http://wiki.ecmascript.org/doku.php?id=harmony:proxies&s=proxy

They aren't in JavaScript yet, at least not in any current web browser implementations.