The Keyup Filter in the FromEvent function is malfunctioning and not behaving as anticipated

I have created a simple search function for my app using the FromEvent KeyUp and debounceTime features as shown in the code below:

<input matInput #inputSearch>

@ViewChild('inputSearch', { static: false }) input: ElementRef;

fromEvent(this.input.nativeElement, 'keyup')
      .pipe(
        filter((val: any) => val.target.value.length > 3),
        debounceTime(500),
        distinctUntilChanged(),
        switchMap((val: any) => this.userService.get(val.target.value))
      )
      .subscribe(data => {
        console.log(data);
      });

Although the search function is triggered when something is typed in the input box, the filter I applied to only execute the API call when the input value is greater than 3 does not seem to be working properly.

I am currently stuck on this issue. Any suggestions? Thank you!

Answer №1

Avoid using fromEvent and keyup. Instead, consider utilizing a more convenient method recommended by Angular. You can utilize Angular Forms and valueChanges as shown below to achieve your desired outcome.

HTML

<div [formGroup]="myGroup">
  <input formControlName="search" type="text" placeholder="search">
</div>

Define your FormGroup in the Component as follows.

myGroup: FormGroup;

this.myGroup = new FormGroup({
   search: new FormControl()
});

You can then subscribe to the value changes of the search FormControl like this.

this.myGroup.get('search').valueChanges.debounceTime(500)
  .subscribe((val: any) => {

    const search = val.trim();
    if (search.length > 3) {
      console.log('Search Term => ', search);
      // TODO: Handle your API Call Here.
    }
});

Check out a functional StackBlitz demo here.

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