Angular Reactive Forms: Detect user input before the value changes

Question

I know that you can use the valueChanges observable in Angular Reactive Forms to detect if a value in the input field has already changed:

inputControl.valueChanges.subscribe(() => {
    // fires when the input value has actually changed
});

However, is there a way to subscribe to an observable of when the user has pressed a key, before the value changes in the input?

I need to do this so I can apply dynamic validation, for example:

User presses a key
I need to know what that key is before I apply validation
Validation then works on the changed value of the input

Florian · Accepted Answer · 2019-07-15 11:33:35Z

2

is there a way to subscribe when the user has pressed a key, before the value changes in the input?

onkeyup event :

 <input formControlName="yourcontrol" (keyup)="onKeyUp($event)">

EDIT :

You need subscribe to event keyup on your AbstractControl elememnt.

see the stackblitz

You could also create a directive to access your element using ElementRef regarding what your requirements are.

edited Jul 15, 2019 at 11:33

answered Jul 15, 2019 at 9:36

Florian

1,44811 silver badges16 bronze badges

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

2 Comments

shrewdbeans Over a year ago

Thanks, but I want to subscribe to keypresses on the form control only, not on the whole document.

shrewdbeans Over a year ago

Thanks again, but the example isn't a subscription to an observable (e.g. like in the valueChanges example), which is what I'm looking for. I'll try to make my question more clear on that. If it's definitely not possible that way, please include that your answer.

Collectives™ on Stack Overflow

Angular Reactive Forms: Detect user input before the value changes

1 Answer 1

EDIT :

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

EDIT :

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related