Passing object as parameter to constructor function and copy its properties to the new object?

Question

I have a JavaScript constructor like this:

function Box(obj) {     this.obj = obj; } 

which i want to pass an object as a parameter like this:

var box = new Box({prop1: "a", prop2: "b", prop3: "c"}) 

and gives me something like this:

box.obj.prop1 box.obj.prop2 box.obj.prop3 

but I would like the properties to be directly on the object like this:

box.prop1 box.prop2 box.prop3 

I know I could do something like this:

function Box(obj) {     this.prop1 = obj.prop1;     this.prop2 = obj.prop2;     this.prop3 = obj.prop3; } 

But that is not good because then my constructor would have to "know" before the names of the properties of the object parameter. What I would like is to be able to pass different objects as parameters and assign their properties directly as properties of the new custom object created by the constructor so I get box.propX and not box.obj.propX. Hope I am making myself clear, maybe I am measing something very obvious but I am a newbie so please need your help!

Thanks in advance.

Answer 1

You could do this. There is probably also a jquery way...

function Box(obj) {   for (var fld in obj) {     this[fld] = obj[fld];   } } 

You can include a test for hasOwnProperty if you've (I think foolishly) extended object

function Box(obj) {    for (var fld in obj) {      if (obj.hasOwnProperty(fld)) {        this[fld] = obj[fld];      }    }  } 

Edit

Ah, ha! it's jQuery.extend

So, the jQuery way is:

function Box(obj) {   $.extend(this, obj); } 

Answer 2

Simply put this in your constructor

  for (var prop in obj) {     if (obj.hasOwnProperty(prop)) {       this[prop] = obj[prop];     }   }