Detect change in a variable?

Question

Is it possible to detect change in a variable?

I have the following:

@Input('name') name: string;

I would like to call a function whenever change is happened in this variable 'name'.

Is it possible?

score 8 · Answer 1 · answered May 05 '18 at 07:50

8

You can do it the following:

private _name = '';

@Input('name')
set name(name: string) {
   this._name = name;
   doSomeStuff();
}

get name(): string { return this._name; }

answered May 05 '18 at 07:50

Mathias

score 3 · Answer 2 · answered May 11 '20 at 00:36

3

I am solve this question using default Angular feature named OnChanges, very similar to OnInit.

answered May 11 '20 at 00:36

mariane muniz

This is in fact the correct answer. Now sure why it was voted down! Direct link to Angular document: https://angular.io/api/core/OnChanges – Sarang Aug 07 '20 at 10:54
Further to my comment above, I implemented this mechanism and realized that `OnChanges` is not triggered if change is made outside of the views. A good explanation is here: https://medium.com/@isaacplmann/ngonchanges-only-runs-when-the-input-change-comes-from-a-template-binding-like-component-8797b759ba0b From this point of view, I would say the get / set solution in blog above or by @Mathias is better, but I don't like the use of private variable. – Sarang Aug 07 '20 at 11:16

2 Answers2