js数组一些基础使用方法

var arr =[];
arr.push("新元素");

//删除数组中指定元素“2”

　　var arr = [1,2,5,8,20,19];
　　var arr1 = arr.splice(arr.indexOf(2),1);
　　console.log(arr); //[1, 5, 8, 20, 19]
　　console.log(arr1); //[2]

var arr = [1,2,5,8,5,5,20,19,5];
var temp = new Set(arr);
arr = Array.from(temp);
console.log(arr);// [1, 2, 5, 8, 20, 19]         

var arr = [1,2,3];
//方式1
arr = [];
//方式2
arr.length = 0

var arr = [1,2,5,8,5,5,20,19,5];
arr = arr.join(",")
console.log(arr); // 1,2,5,8,5,5,20,19,5