Angular 2 how to prevent data binding for specific variable

Question

So I need to prevent data binding for a specific variable. I want to do it like this:

// data is mostly an object in my case.
// it would be nice if there's a global solution
function(data) {
    d = data; // variable that changes on user input
    oldD = data; // variable that shouldn't change on user input
}

but whenever I implement code like this the oldD variable will change when the d variable gets changed. And I would like to prevent this from happening. But how do I prevent such a thing?

What kind of variable is data? Is it a primitiv type (number, string, boolean), an array, or an object with properties? — Martin Parenteau
– Martin Parenteau, Commented Mar 23, 2018 at 14:11

Dheeraj Kumar · Accepted Answer · 2018-03-23 14:16:54Z

3

You need to assign value without assigning reference of old object.

Here's solution for JavaScript/Angular.

let oldD = Object.assign({}, data);

Hope this helps.

answered Mar 23, 2018 at 14:16

Dheeraj Kumar

4,2559 gold badges51 silver badges83 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Berend Hulshof Over a year ago

Thank you, this helped, can you give some additional information on how it works?

Dheeraj Kumar Over a year ago

When you use equal sign to copy values, it actually assigns the reference of data. That is how binding works. Multiple vars with same reference. By Object.assign() you just copy the value without the actual reference. So your oldD will have a new reference of its own and hence will not change.

Berend Hulshof Over a year ago

oh ok, so the brackets indicate the target

Amit Chigadani · Accepted Answer · 2018-03-23 14:28:07Z

0

Probably you are looking for, How to clone object.

function(data) {
    d = data; // variable that changes on user input  

    // creates brand new object with the same data
    let oldD = Object.create(data.constructor.prototype);
    data.constructor.apply(oldD);
}

answered Mar 23, 2018 at 14:28

Amit Chigadani

29.9k14 gold badges88 silver badges102 bronze badges

2 Comments

Berend Hulshof Over a year ago

Dheeraj's solution is a bit more efficient and it worked, but thanks for the answer

Amit Chigadani Over a year ago

You can also look at the difference here to get more idea. stackoverflow.com/questions/34838294/…

Collectives™ on Stack Overflow

Angular 2 how to prevent data binding for specific variable

2 Answers 2

3 Comments

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related