代码之家 › 专栏 › 技术社区 › Bernhard

在angular中通过模板级交互更新“autofocus”属性

angular html

Bernhard · 技术社区 · 7 年前

对工作有问题吗 autofocus 属性与角度。在细节上我有一个 <form> <input type="text"> 在最上面,最初被一个条件聚焦。

<input [attr.autofocus]="selection===-1"
       [(ngModel)]="myForm.firstInpElem" 
       name="firstInpElem" 
       placeholder="firstInpElem">

然后窗体将在由 <input type="radio"> .

一旦做出选择,就会显示相应的元素,然后应该得到 自动对焦 .

但这并没有发生,我也不明白为什么会这样。

准备 stackblitz with a working example 但主要是下面的标记将不会像预期的那样工作

<h1>Forms example</h1>

<form>

  <pre>Condition to focus "firstInpElem" is {{selection===1|json}}</pre>

  <p>This input element is autofocussed on page load</p>

  <p>
    <input [attr.autofocus]="selection===-1"
           [(ngModel)]="myForm.firstInpElem" 
           name="firstInpElem" 
           placeholder="firstInpElem">
  </p>

  <p>
    Provide one of both information:<br>

    <label>
      <input [(ngModel)]="selection" 
             name="radioInpElem"
             type="radio"
             [value]="1"> 
             Option 1
    </label>
    <br>

    <label>
      <input [(ngModel)]="selection" 
             name="radioInpElem"
             type="radio"
             [value]="2">
             Option 2
    </label>

  </p>

  <pre>Condition to focus "secondInpElem" is {{selection===1|json}}</pre>
  <pre>Condition to focus "thirdInpElem" is {{selection===2|json}}</pre>
  <p>


  <input *ngIf="selection===1"
        [attr.autofocus]="selection===1"
        [(ngModel)]="myForm.secondInpElem"
        name="secondInpElem"
        placeholder="secondInpElem">



  <input *ngIf="selection===2"
          [attr.autofocus]="selection===2"
          [(ngModel)]="myForm.thirdInpElem"
          name="thirdInpElem"
          placeholder="thirdInpElem">
  </p>
</form>


<pre>{{myForm|json}}</pre>

2 回复 | 直到 7 年前

ConnorsFan 7 年前

如果您签入开发工具(F12工具),您将看到新的输入控件实际上获得了 autofocus 自动对焦 when the page loads . 在您的例子中,当新元素可见时,页面已经被加载。

相反,您可以通过编程方式将焦点设置在新的输入元素上。为此,可以为具有 ngIf 条件:

<input #inputElement *ngIf="selection === 1"
      [(ngModel)]="myForm.secondInpElem"
      name="secondInpElem"
      placeholder="secondInpElem">

<input #inputElement *ngIf="selection === 2"
        [(ngModel)]="myForm.thirdInpElem"
        name="thirdInpElem"
        placeholder="thirdInpElem">

并用计算机监控这些元素的存在 ViewChildren 以及 QueryList.changes 事件。每次一个输入元素变为可见时,您都会将焦点设置在该元素上:

@ViewChildren("inputElement") inputElements: QueryList<ElementRef>;

ngAfterViewInit() {
  this.inputElements.changes.subscribe(() => {
    this.inputElements.last.nativeElement.focus();
  });
}

看到了吗 this stackblitz

Eliseo 7 年前

另一个选项是隐藏输入(不使用*ngIf else)显示.样式)和参考变量看见 https://stackblitz.com/edit/angular-sbc4pp?file=src%2Fapp%2Fapp.component.html

    <label>
      <input [ngModel]="selection" (change)="change(second,1)" 
             name="radioInpElem"
             type="radio"
             [value]="1"> 
             Option 1
    </label>
    <br>
    <label>
      <input [ngModel]="selection" (change)="change(third,2)"
             name="radioInpElem"
             type="radio"
             [value]="2">
             Option 2
    </label>

  <input #second [style.display]="selection===1?'inherit':'none'"
        [(ngModel)]="myForm.secondInpElem"
        name="secondInpElem"
        placeholder="secondInpElem">

  <input #third [style.display]="selection===2?'inherit':'none'"
          [(ngModel)]="myForm.thirdInpElem"
          name="thirdInpElem"
          placeholder="thirdInpElem">

  change(element:any,index:number)
  {
  this.selection=index;
  setTimeout(()=>{element.focus()},0);
  }