获取 *ngFor 中的文本长度

Question

我对 Angular (8) 还很陌生，我尝试获取输入值的长度，我以*ngFor如下方式创建了它：<div *ngFor="let panel of panels; index as i" class="panel" [id]="'panel-' + panel.id">    <div>{{ panel.title }}</div>    <input matInput placeholder="Bezeichnung" [(ngModel)]="panel.title" /></div>我将如何访问panel.title班级中的长度？这是我的接口/类export interface ProgressbarStepData {    // Each progressbar step is represented by an instance of this data type.    id: number; // Unique ID    title: string; // The label that is displayed as the step title.    color: string; // Hex code of the colored markings associated with this step. Only visible in Builder, not Viewer.    order: number; // Denotes which step this is (from step 1 to <number of steps>)}export class ProgressbarEditorComponent implements OnInit {    public panels: Array<ProgressbarStepData> = []; // One panel for each existing progressbar step   ...我需要什么才能获得当前输入的输入长度？编辑澄清我想要实现的目标：我想计算在 CURRENT 输入中键入的字符数并触发来自类的警报（而不是来自模板本身）

Answer 1

.html

<input type="text" (input)="inputMthd($event)"  (keyup)="methodCalled($event)">

.ts

inputMthd(e){

console.log(e);

event.target.value.length;

}

methodCalled(e){

console.log(e);

e.target.value.length;

}

Answer 2

您ngModel需要绑定到panels不panel中ngFor。您可以使用index.

<div *ngFor="let panel of panels; index as i" class="panel" [id]="'panel-' + panel.id">

    <div>{{ panel.title }}</div>

    <input matInput placeholder="Bezeichnung" [(ngModel)]="panels[i].title" (blur)="showAlert(i)" />

</div>

然后通过传入索引并使用它来获取面板标题的长度来触发组件中的警报。我在blur这里使用了这个事件。

showAlert(index) {

    const titleLength = this.panels[index].title.length;

    // Call alert with the length of the title here.

}

Answer 3

尝试这个，

<div *ngFor="let panel of panels; index as i" class="panel" [id]="'panel-' + panel.id">

    <div>{{ panel.title }}</div>

    <input (change)="onChange({{panel.title}})" matInput placeholder="Bezeichnung" [(ngModel)]="panel.title" />

</div>

onChange(title) {

          console.log(title.length);

         })