Angular 4, How to update [(ngModel)] with a 1 second delay

Question

Since ngModel instantly updates the delay setting method.

  <input type="text" value="{{item.task_name}}" name="task_name" [(ngModel)]="item.task_name" (ngModelChange)="update_fields([item.task_name])" >

I need to save the task_name with a delay of one second by calling update_fields () to avoid instant calls for maintenance.

thank

Answer 1

Rxjs and Observables - the perfect candidate for this type of task! Here is an example of how this can be achieved:

Template:

<input type="text" [value]="item.task_name"(keyup)="term$.next($event.target.value)">

component:

import ......

import {Subject} from 'rxjs/Subject';
import 'rxjs/add/operator/debounceTime';
import 'rxjs/add/operator/distinctUntilChanged';
import 'rxjs/add/operator/switchMap';

@Component{(
  ...
)}
export class YourComponent {

  term$ = new Subject<string>();

  constructor() {
    this.term$
      .debounceTime(1000)
      .distinctUntilChanged()
      .switchMap(term => /*do something*/);
  }
}

subject- This is a type of object that acts as observable and observant, that is, you can subscribe to it and emit values ​​from it (with next())!

debounceTime ,

distinctUntilChanges

switchMap ,

Answer 2

Angular 6:

:

<input type="text" [value]="item.task_name" (keyup)="term$.next($event.target.value)">

:

import ......

import { Subject, EMPTY } from 'rxjs';
import { debounceTime, distinctUntilChanged, switchMap } from 'rxjs/operators';

@Component{(
  ...
)}
export class YourComponent implements OnDestroy {

  term$ = new Subject<string>();

  private searchSubscription: Subscription;

  constructor() {
    this.searchSubscription = this.term$.pipe(
      debounceTime(1000),
      distinctUntilChanged(),
      switchMap(term => {
        /*do something*/
        return EMPTY;
      })
    ).subscribe();
  }

  ngOnDestroy() {
    //remember to unsubscribe on destroy

    if (this.searchSubscription) {
      this.searchSubscription.unsubscribe();
      this.searchSubscription = null;
    }
  }
}

Answer 3

update_fields(){

  this.service.yourTask(){
    .subscribe(data => {
      setTimeout(()=>{ //your task }, 4000)
    }    
  }
}


someFunction() {
    setTimeout(() => /* code to execute */, 3000)
}

Answer 4

update_fields().

public update_fields(data)
  setTimeout(function() {
   //call service
  }, 1000);

Answer 5

, .

:

<input ... #element (ngModelChange)="delayAction(element, doSomething, [$event])">

:

    actionsByElements = new Map<HTMLElement, Subscription>();

    delayAction(element: HTMLElement, cb: Function, args: any[]) {
      // cancel countdown by element
      let action = this.actionsByElements.get(element);
      if(action) {
        action.unsubscribe();
      }

      // start new countdown by element
      action = timer(1000).subscribe(() => cb.apply(this, args));
      this.actionsByElements.set(element, action);
    }

    doSomething(){...}