Questions & Answers

Angular Valuechanges not firing first time

I have a input button, where onChange, I am calling a function. In that funtion, I am checking for valueChanges. Somehow, the subscribe to the valueChanges is not getting triggered on the first tab out after inputting a value.

Here are some code snippets: HTML:

<input type="text" formControlName='{{}}' 


public fetchData(formControlName: string, fetchData: boolean): void {
if (this.primaryControls.indexOf(formControlName) !== -1 && 
   fetchData) {
  this.uiForm.get(formControlName)?.valueChanges **//fine till here. Gets executed**
    .subscribe(data => { **// This subscribe is not firing**
      if (!this.uiForm.dirty) {
         //do some stuff here
2023-01-20 19:42:02
Is the form control not defined at this point? If you console.log(this.uiform.get(formControlName)) is it undefined?
Answers(2) :

You can make use of distinctUntilChanged() and startWith() inside your pipe.

this.uiForm.get(this.formControlName)?.valueChanges.pipe(debounceTime(1000), distinctUntilChanged(), startWith(this.uiForm.get(this.formControlName).value)).subscribe(...);

Every time your input changes, you are creating a new subscription. Nothing happens at first because no subscriptions exist yet.

Just subscribe to valueChanges once on init. Use a loop if you have multiple.

<input type="text" formControlName='{{}}'/>

I'm assuming subControl is a component property, which might not be true. But I'm sure you get the idea.