How to create properties to and object dynamically based on another object in JavaScript?

Question

I have a scenario where from a source object I need to create a new result object.

The object would need to have exactly all properties from source, with the addition of "methods", with naming based on the properties and code to be executed based on a template (in my case alert(this.x)).

Note: script should keep in consideration any number of properties from source

I would like to know:

Is it possible to do it in JS?
What the appropriate Technics?
Any examples?

FROM SOURCE OBJECT

  var source = {
        a: 'a',
        b: 'b'
    };

I NEED TO GET RESULT OBJ DYNAMICALLY CREATED (BY SOME FUNCTION)

    var result = {
        a: 'a',
        b: 'b',
        _setA: function(){
            alert(this.a);
        },
        _setB: function(){
            alert(this.a);
        }
    }

Note: result is created after processing the source object

EDIT:

final solution based on your answers

http://jsfiddle.net/kbnd6e5c/1/

just for clarification the object result should be created dynamically based on source properties — GibboK
– GibboK, Commented Dec 13, 2014 at 18:04
Should later mutations to source be reflected when calling the methods on result? — six fingered man
– six fingered man, Commented Dec 13, 2014 at 18:13

dfsq · Accepted Answer · 2014-12-13 18:12:04Z

1

You can first use $.extend method to copy properties, and then you need iterate through properties and create dynamic setters. For example like in below code:

var source = { a: 'a', b: 'b' };    
var result = $.extend({}, source);

Object.keys(source).forEach(function(key) {
    result['_set' + key[0].toUpperCase() + key.slice(1)] = function(value) {
        alert(this.key);
        this[key] = value;
    }
});

Check the working demo below.

var source = { a: 'a', b: 'b', test: 'test' };    
var result = $.extend({}, source);
    
Object.keys(source).forEach(function(key) {
    result['_set' + key[0].toUpperCase() + key.slice(1)] = function(value) {
        this[key] = value;
    }
});

alert([ result.a, result.test ]);

result._setA('a1');
result._setTest('test1');

alert([ result.a, result.test ]);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

edited Dec 13, 2014 at 18:12

answered Dec 13, 2014 at 18:00

dfsq

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1 Comment

GibboK Over a year ago

thanks, but I need the _setA and _setB created dynamically based on the properties in source

TotuDoum · Accepted Answer · 2014-12-13 18:00:46Z

0

I'm not sure I have fully understanding your question but I think you should juste use that simple thing:

var copy = result
copy.example = {
    x: Y,
    z, T
}
copy.newFuntion = function(){...} //add your own function

This way you have everything that result have + your own things

answered Dec 13, 2014 at 18:00

TotuDoum

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1 Comment

andrew Over a year ago

copy is not, its a reference, appending to it will also append to the source

Sergio Flores · Accepted Answer · 2014-12-13 18:10:59Z

0

You can do something like this:

var result = {
    a: 'A',
    b: 'B'
};

var copy = result;

Object.keys(result).forEach(function(key) {
    Object.defineProperty(copy, "_set" + key, {
        get: function() {
            return result[key]; 
        }
    })
});

copy._seta;
copy._setb;

Source

answered Dec 13, 2014 at 18:10

Sergio Flores

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1 Comment

GibboK Over a year ago

hi, thanks, but it is not for getting or setting property is for creating dynamically method with some code to be executed inside.

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