数组的两个方法: copyWithin和fill

╰+哭是因爲堅強的太久メ 2023-02-13 03:44 22阅读 0赞

**arr.copyWithin() 在当前数组中，复制一段,替换掉另外一段    ps:会改变原数组,数组长度不变**

参数: target --必选 从该下标开始替换数组项

start --可选 从该下标开始复制数组项，默认为0

end --可选 到该下标停止复制数组项,不包括该位置，默认是Array.length

\[JavaScript\] *纯文本查看* *复制代码*

[?][Link 1]

<table> 
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     <span style="color:#363636;"><span style="color:#afafaf;">1</span></span> 
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     <span style="color:#363636;"><span style="color:#afafaf;">2</span></span> 
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     <span style="color:#363636;"><span style="color:#afafaf;">3</span></span> 
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      <span style="color:#363636;"><code>[/align][align=left] let arr = [1, 2, 3, 4, 5, 6, 7]</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>&nbsp;</code><code>let arr1 = arr.copyWithin(1)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>&nbsp;</code><code>console.log(arr1)&nbsp;&nbsp; </code><code>// [1, 1, 2, 3, 4, 5, 6]</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>&nbsp;</code><code>console.log(arr)&nbsp;&nbsp;&nbsp; </code><code>// [1, 1, 2, 3, 4, 5, 6]</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>&nbsp;</code><code>let arr2 = arr.copyWithin(1, 2)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>&nbsp;</code><code>console.log(arr2)&nbsp;&nbsp; </code><code>// [1, 2, 3, 4, 5, 6, 6]</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>&nbsp;</code><code>let arr3 = arr.copyWithin(1, 2, 4)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>&nbsp;</code><code>console.log(arr3)&nbsp;&nbsp; </code><code>// [1, 3, 4, 4, 5, 6, 6][/align][align=left]</code></span> 
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**arr.fill() 使用给定的值，填充一个数组       ps:会改变原数组**

参数： target -- 用于填充的值

start --可选 从该下标开始填充，默认为0

end --可选 到该下标停止填充,不包括该位置，默认是Array.length

\[JavaScript\] *纯文本查看* *复制代码*

[?][Link 1]

<table> 
 <tbody> 
  <tr> 
   <td style="text-align:left;vertical-align:baseline;"> 
    <div style="margin-left:0px;"> 
     <span style="color:#363636;"><span style="color:#afafaf;">1</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#363636;"><span style="color:#afafaf;">2</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#363636;"><span style="color:#afafaf;">3</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#363636;"><span style="color:#afafaf;">4</span></span> 
    </div> 
    <div style="margin-left:0px;"> 
     <span style="color:#363636;"><span style="color:#afafaf;">5</span></span> 
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    <div style="margin-left:0px;"> 
     <span style="color:#363636;"><span style="color:#afafaf;">6</span></span> 
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     <span style="color:#363636;"><span style="color:#afafaf;">7</span></span> 
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     <span style="color:#363636;"><span style="color:#afafaf;">8</span></span> 
    </div> </td> 
   <td style="text-align:left;vertical-align:baseline;"> 
    <div style="margin-left:0px;"> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>let arr = [1, 2, 3, 4, 5]</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>let arr1 = arr.fill(</code><code>'哼'</code><code>)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>console.log(arr1)&nbsp; </code><code>// ['哼', '哼', '哼','哼', '哼']</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>console.log(arr)&nbsp;&nbsp; </code><code>// ['哼', '哼', '哼', '哼', '哼']</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>let arr2 = arr.fill(</code><code>'哈'</code><code>, 2)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>console.log(arr2)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; </code><code>// ['哼', '哼', '哈', '哈', '哈']</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>let arr3 = arr.fill(</code><code>'略略略'</code><code>, 1, 3)</code></span> 
     </div> 
     <div style="margin-left:0px;"> 
      <span style="color:#363636;"><code>console.log(arr3)&nbsp;&nbsp;&nbsp;&nbsp; </code><code>// ['哼', '略略略', '略略略', '哈', '哈']</code></span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
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[Link 1]: http://bbs.itheima.com/#