题解 | #添加元素#

{"html":"<!-- 请在此处编写你的代码 -->\\n<!-- <div id=\"app\"> Hello Nowcoder </div> -->","css":"/* html, body {\\n\\twidth: 100%;\\n\\theight: 100%;\\n\\tmargin: 0;\\n\\tpadding: 0;\\n} */","js":"function prepend(arr, item) {\r\n         let ans=arr.slice();\r\n         ans.unshift(item);\r\n         return ans;\r\n}"}

javaScript浅拷贝数组的几种方法：

1.let newArr=oldArr.slice()

2.let newArr=Array.from(oldArr);

3.let newArr=oldArr.concat();

4.let newArr=[...oldArr];

5.let newArr = oldArr.map(x => x);