join(separator)
var arr = ["旋之华", 18, "男"];
var str = arr.join("|");
console.log(str);
console.log(typeof str); // string
console.log(arr);
将数组的元素组成一个字符串，以separator为分隔符，默认为,
1 // push()和pop() 数组的最后操作
2 var arr = ["张三", "李四", "王五"];
3 var count = arr.push("赵六", "宋小宝");
4 console.log(count);
5 console.log(arr);
6
7 var item = arr.pop();
8 console.log(item);
9 console.log(arr);
1 var arr = ["张三", "李四", "王五"];
2 console.log(arr.reverse());
3 console.log(arr);
1 concat()
2 var arr = [1, 3, 5, 7, 9];
3 var copyArr = arr.concat(11, "王小二", ["张三", "李四"]);
1 // shift() 和 unshift() shift()是删除第一项，返回被删除元素的值，如果数组为空返回Undefined unshift返回数组的长度
2 var arr = ["张三", "李四", "王五"];
3 console.log(arr.shift());
4 console.log(arr.shift());
5 var count = arr.unshift("小沈阳", "宋小宝");
1 // indexOf()和 lastIndexOf()
2 var arr = [2, 4, 6, 8, 8, 6, 4, 2];
3 console.log(arr.indexOf(4, 2));//-1
4 console.log(arr.indexOf(4)); //1
5 console.log(arr.lastIndexOf(4)); //6 从后往前找
6 console.log(arr.indexOf("4")); // -1
7 console.log(arr.lastIndexOf("4")); // -1
