javascript - Replace an object with another one

Question

var obj1 = New MyObject('Object 1');
var obj2 = New MyObject('Object 2');

var foo = { anObject : obj1 };

foo.anObject = obj2;
console.log(obj1.name);

Naturally, obj1 didn't changed. But how to replace obj1 by obj2 in the whole script assuming I can only access foo ?

Your code + use foo.anObject instead of obj1 when referencing it. — Fabrício Matté
– Fabrício Matté, Commented Aug 24, 2013 at 17:12
@BillyMoon @Bergi I'd just like a pointer. In C, it should be foo.anObject = &obj1 and then *(foo.anObject) = obj2 — Lithy
– Lithy, Commented Aug 25, 2013 at 0:07

Andreas Louv · Accepted Answer · 2014-10-02 12:36:00Z

5

You should remove all properties in obj1 and then add all properties from obj2. But note that obj1 wont hold the reference to the same object as obj2 but make a new cloned one. Also note the below is shallow cloning with a as target:

var replaceObject = function(a, b) {
    var prop;

    for ( prop in a ) delete a[prop];
    for ( prop in b ) a[prop] = b[prop]; 
};

var a = {a: 1},
    b = {b: 2};

replaceObject(a, b);

a // {b: 2};
// but:
a === b // false

edited Oct 2, 2014 at 12:36

answered Aug 24, 2013 at 17:08

Andreas Louv

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3 Comments

gion_13 Over a year ago

It's not really the ideal solution, but it's not the ideal case eather. +1 for a simple and clean solution

Lithy Over a year ago

It works for what I do now, but isn't there a cleaner solution ?

Dapeng Li Over a year ago

Should the loop body in line 5 be 'a[prop] = b[prop];'?

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