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 = ''; this.value2 = new Number(inputRef.value); if ( this.value2 > 0 ) { alert('輸入正確'); } else { alert('請輸入大於0的數字'); } } addNumber2(inputRef: HTMLInputElement): void { console.log(inputRef.value); inputRef.value = ''; this.value2 = new Number(inputRef.value); if ( this.value2 !== Number ) { alert('只能輸入數字'); } else { alert('輸入正確'); } } addNumber3(inputRef: HTMLInputElement): void { console.log(inputRef.value); inputRef.value = ''; this.value2 = new Number(inputRef.value); if ( this.value2 !== Number ) { alert('只能輸入數字'); } else { alert('輸入正確'); } } constructor() { } ngOnInit() { } }