Javascript 创建自定义输入字段

我有一个电话屏蔽指令，它屏蔽了美国标准中的电话号码。(000) 000-0000 我用正则表达式做的

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但我想在输入字段的焦点上显示这样的输入字段（）\uu-\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu），然后我键入。如何制作？

制作

PhoneMaskDirective

   constructor(public ngControl: NgControl) { }

  @HostListener('ngModelChange', ['$event'])
  onModelChange(event) {
    this.onInputChange(event, false);
  }

  @HostListener('keydown.backspace', ['$event'])
  keydownBackspace(event) {
    this.onInputChange(event.target.value, true);
  }


  onInputChange(event, backspace) {
    let newVal = event.replace(/\D/g, '');
    if (backspace && newVal.length <= 6) {
      newVal = newVal.substring(0, newVal.length - 1);
    }
    if (newVal.length === 0) {
      newVal = '';
    } else if (newVal.length <= 3) {
      newVal = newVal.replace(/^(\d{0,3})/, '($1)');
    } else if (newVal.length <= 6) {
      newVal = newVal.replace(/^(\d{0,3})(\d{0,3})/, '($1) ($2)');
    } else if (newVal.length <= 10) {
      newVal = newVal.replace(/^(\d{0,3})(\d{0,3})(\d{0,4})/, '($1) ($2)-$3');
    } else {
      newVal = newVal.substring(0, 10);
      newVal = newVal.replace(/^(\d{0,3})(\d{0,3})(\d{0,4})/, '($1) ($2)-$3');
    }
    this.ngControl.valueAccessor.writeValue(newVal);
  }

构造函数（公共ngControl:ngControl）{
@HostListener（'ngModelChange'，['$event']））
onModelChange（事件）{
此.onInputChange（事件，false）；
}
@HostListener（'keydown.backspace'，['$event']））
keydownBackspace（事件）{
此.onInputChange（event.target.value，true）；
}
onInputChange（事件，退格）{
让newVal=event.replace（/\D/g'）；
如果（backspace&&newVal.length，则可以使用此库：

您只需在.ts文件中配置掩码：

 config = {
    mask:['(', /\d/, /\d/, /\d/, ')', ' ', /\d/, /\d/, /\d/, '-', /\d/, /\d/, /\d/, /\d/],
    guide: true,
    showMask: true 
 }

在模板中：

<input [textMask]="config" [(ngModel)]="myModel" type="text"/>



您可以在此处看到一个工作示例：

在此处发布您尝试过的代码。如果可能，也可以通过在…中创建工作示例来发布链接。您尝试过什么？请参见此处..我已经完成了部分..我希望输入字段为（\uuuuu）当用户聚焦输入字段时，嘿，谢谢你…angular-tmwana.stackblitz.io请看这里..我已经完成了部分…我希望输入字段是（uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu？