Angular progress bar not moving with value change-CodePudding

I'm trying to implement a progress bar that moves in accordance with a process that's running in my Angular program.

<div mat-dialog-content>
        <mat-progress-bar mode="determinate" [value]="loadingVal"></mat-progress-bar>

</div>

var loadingVal = 0 
var increase = 100 / array.length

for (i = 0, array.length, i  ) {
    ....
    this.loadingVal = this.loadingVal   increase
}

As you can see, I am increasing the loadingVal with every iteration of the loop. However, the progress bar is not moving, it is staying at 0 until the process is complete. Am I doing something wrong, or is there another way to move the progress bar along?

CodePudding user response：

This cannot work that way because JavaScript is single-threaded. Angular will run its change detection after the complete function returns. If you want to see some progress, try to use window.setTimeout(() => this.loadingVal = increase, 500 * i); within your loop. The setTimeout() function will queue those callbacks and Angular can perform the change detection in between.

Example

Controller:

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent implements OnInit {

  loadingVal: number = 0;

  ngOnInit(): void {
    for (let i = 0; i < 100; i  ) {
      window.setTimeout(() => (this.loadingVal  = 1), i * 100);
    }
  }
}

Template:

  <mat-progress-bar mode="determinate" [value]="loadingVal"></mat-progress-bar>

Working example: https://stackblitz.com/edit/angular-ivy-kciqoy

CodePudding user response：

I think that it should be

[value]="loadingVal"

instead of

[value]=loadingVal