angular 表单验证

1. 只能输入整型

<input matInput formControlName="value" (keypress)="validateNum($event)" trim="blur">

  validateNum(event) {
    const pattern = /[0-9\+\-\ ]/;
    let inputChar = String.fromCharCode(event.charCode);
    if (event.keyCode != 8 && !pattern.test(inputChar)) {  //8: delete 45: -
      event.preventDefault();
    }
  }