如何从html中的textarea获取输入到Angular中的.ts

Question

I am a newbie in Angular and now I want to get user input from a textarea but I fail to do so.

Updated: ng-model="num1" > [(ngModel)]="num1"

HTML:

<span><input [(ngModel)]="num1" type="text" placeholder="Enter value"></span>
     // user enter one number

<span><input type="text" readonly value={{answer}}></span></p>

<button class="result" (click)=onSelectEqual()>=</button>
     // click this button to get the value that user entered

.ts:

num1 : number;
answer: number;

onSelectEqual(){
  this.answer = this.num1 + 1 ;
}

Answer 1

In angular, for two-way binding you have to enclose ngModel in [()] . See - https://angular.io/api/forms/NgModel .

<span><input [(ngModel)]="num1" type="text" placeholder="Enter value"></span>

Answer 2

Use [(ngModel)] instead of ng-model in your html template. ng-model is the syntax of Angularjs which will not work in Angular2+.

Also make sure to import FormsModule in app.module.ts

import { FormsModule } from '@angular/forms';

Also add it to the imports array in app.module.ts

imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule
  ],

This is important as without the FormsModule, angular will not be able to identify the ngModel directive.

On a different note, the input will return the value typed by the user as a string. To read it as a number and add 1 to it, you will have to typecast it:

onSelectEqual(){
  this.answer = Number(this.num1) + 1 ;
}

Please also note that // for comments doesn't work in html template, use <!-- --> instead.