<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>不影响原数组方法</title>
</head>
<body><script>// concat 拼接var arr1 = [1,2,3]var arr2 = [4,5,6]var arr3 = arr1.concat(arr2,7,[8,9])console.log(arr1,arr2,arr3)// join 数组转化成字符串var arr = [1,2,3,4,5]// 通过--连接document.write(arr.join("--"))// slice截取var arr4 = ["aaa","bbb","ccc","ddd","eee"]// 包前不包后var arr5 = arr4.slice(0,2)// 从下标2到最后，如果不传参就是全部var arr6 = arr4.slice(2)console.log(arr4,arr5,arr6)// indexOf -1找不到 存在元素就输出索引var arr7 = ["qq","ww","ee","rr","tt","qq"]var a = arr7.indexOf("444")var b = arr7.indexOf("rr")console.log(a,b)// lastIndexOf -1找不到 从后往前找存在元素就输出索引 var c = arr7.lastIndexOf("6666")var d = arr7.lastIndexOf("qq")// 从下标3的位置往前找var e = arr7.lastIndexOf("qq",3)console.log(c,d,e)</script>
</body>
</html>
