javascript - document.getElementById 不返回任何值

Question

我正在使用 TypeScript，并尝试创建一个脚本来获取带有 class 和 id 的 div 的 HTML 值。

但是，我能够获取类的结果，但无法使用 getElementById 获取结果。

html 如下所示:

<button (click)="selectDiv()">select div</button>

   <div class="container"  id="main-wrapper">   
<p>
 Fetch me
</p>
</div> 

以及 explore.ts 文件

selectDiv() {
     //create a new HTMLElement from nativeElement
    var hElement: HTMLElement = this.elRef.nativeElement;

    //now you can simply get your elements with their class name
   var allDivs = hElement.getElementsByClassName('container')[0];

   var getSection = <HTMLElement>document.getElementById["main-wrapper"].innerHTML;

    console.log(allDivs);
    console.log(getSection); // returning nothing
  }

getsection 给我一个错误，如下所示:

ERROR TypeError: Cannot read property 'innerHTML' of undefined

Answer 1

function selectDiv() {
     //create a new HTMLElement from nativeElement
   // var hElement: HTMLElement = this.elRef.nativeElement;

    //now you can simply get your elements with their class name
   var allDivs = document.getElementsByClassName('container')[0];

   var getSection = document.getElementById("main-wrapper").innerHTML;

    console.log(allDivs);
    console.log(getSection); // returning nothing
  }

<button onclick="selectDiv()">select div</button>

   <div class="container"  id="main-wrapper">   
<p>
 Fetch me
</p>
</div>