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.

See also: stackoverflow.com/questions/2266789/…

Christian C. Salvadó
– Christian C. Salvadó

2011-12-08 22:10:25 +00:00
Commented Dec 8, 2011 at 22:10 — Christian C. Salvadó
– Christian C. Salvadó, Commented Dec 8, 2011 at 22:10

Adilson de Almeida Jr · Accepted Answer · 2011-12-08 20:58:14Z

2

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

answered Dec 8, 2011 at 20:58

Adilson de Almeida Jr

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Comments

Naftali · Accepted Answer · 2011-12-08 20:56:45Z

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/

answered Dec 8, 2011 at 20:56

Naftali

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Comments

Dhwanit · Accepted Answer · 2013-08-10 19:11:45Z

1

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 );

edited Aug 10, 2013 at 19:11

answered Aug 10, 2013 at 14:22

Dhwanit

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Comments

Jamund Ferguson · Accepted Answer · 2011-12-08 21:04:48Z

0

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.

answered Dec 8, 2011 at 21:04

Jamund Ferguson

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