p4.component.ts

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

@Component({
  selector: 'app-p4',
  templateUrl: './p4.component.html',
  styleUrls: ['./p4.component.css']
})
export class P4Component implements OnInit {

  number = '';
  value2: any;

  addNumber(inputRef: HTMLInputElement): void {
    console.log(inputRef.value);
    inputRef.value = '';

    inputRef.value = this.value2;

    if (
      this.value2 = 0
    ) {
      alert('good');
    } else {
    alert('請輸入0');
    }
  }



  constructor() { }

  ngOnInit() {
  }

}