javascript - 请解释此 JavaScript 代码如何删除所有节点

Question

HTML

<ul id="myList">
   <li>Item 1</li>
   <li>Item 2</li>
   <li>Item 3</li>
   <li>Item 4</li>
</ul>

我似乎无法理解此while语句如何删除上述列表中的所有节点。有人可以解释一下吗？

JavaScript

while(myList.firstChild) {
    myList.removeChild(myList.firstChild)
};

Answer 1

边读边读

HTML

<ul id="myList">
   <li>Item 1</li>
   <li>Item 2</li>
   <li>Item 3</li>
   <li>Item 4</li>
</ul>

js代码

while(myList.firstChild) // loop will run while myList has a firstChild
    {myList.removeChild(myList.firstChild)
};

运行

1st time while loop run firstChild is <li>Item 1</li> --> code runs and remove it.

现在 HTML

<ul id="myList">
   <li>Item 2</li>
   <li>Item 3</li>
   <li>Item 4</li>
</ul>

跑

2nd time while loop run firstChild is <li>Item 2</li> --> code runs and remove it.

现在 HTML

<ul id="myList">
   <li>Item 3</li>
   <li>Item 4</li>
</ul>

跑

3rd time while loop run firstChild is <li>Item 3</li> --> code runs and remove it.

现在 HTML

<ul id="myList">
   <li>Item 4</li>
</ul>

跑

4th time while loop run firstChild is <li>Item 4</li> --> code runs and remove it.

现在 HTML

<ul id="myList">
</ul>

跑

js 代码不会运行，因为myList. While 循环条件失败。