Question

138

Replace a one javascript object with another object

rated 0 times [ 144] [ 6] / answers: 1 / hits: 46107 / 12 Years ago, tue, december 18, 2012, 12:00:00

On page load I am creating two Javascript Objects, objDemo1 and objDemo1Backup where the latter is simply an exact copy of the first.

e.g.

objDemo1 { 

    sub_1 = { something: 123, somethingElse: 321 },

    sub_2 = { something: 456, somethingElse: 654 }

}

I can modify the values in sub_ as well as add / delete new sub_'s but the only object I am editing is objDemo1. i.e. I never change objDemo1Backup

I have a reset button that when clicked will reset objDemo1 back to what it was when the page originally loaded (i.e. objDemo1 = objDemo1Backup). This is where I am having the issue..

How do I set objDemo1 to objDemo1Backup?

I have tried:

objDemo1 = objDemo1Backup;

and

objDemo1 = null;

var objDemo1 = objDemo1Backup;

...as well as similar variations but nothing seems to work.
Any ideas?

Note: I can confirm that at the point of resetting, objDemo1Backup is exactly the same as it was when I created it and objDemo1 has changed.

My code is definetly hitting the reset functionality, where I've tried the objDemo1 = objDemo1Backup... I just cannot figure out the syntax to replace the object.

Answers

Only authorized users can answer the question. Please sign in first, or register a free account.

maurodannyr

Add To Favorites

Follow

Total Points: 126

Total Questions: 103

Total Answers: 105

Location: Maldives

Member since Sun, Feb 27, 2022

2 Years ago

answered 12 Years ago orlando · Accepted Answer

In JavaScript objects are passed by reference, never by value. So:

var objDemo, objDemoBackup;

objDemo = {

    sub_1: foo;

};

objDemoBackup = objDemo;

objDemo.sub_2 = bar;

console.log(objDemoBackup.sub_2);   // bar

To get a copy, you must use a copy function. JavaScript doesn't have one natively but here is a clone implementation: How do I correctly clone a JavaScript object?

var objDemo, objDemoBackup;

objDemo = {

    sub_1: foo;

};

objDemoBackup = clone(objDemo);

objDemo.sub_2 = bar;

console.log(objDemoBackup.sub_2);   // undefined