JavaScript 数组

var arr = [1, 2, 3, 5];
        Array.prototype.push = function () {
            for (var i = 0; i < arguments.length; i++) {
                arr[arr.length] = arguments[i];
            }
        }

  //pop 剪切最后一位
        var arr = [1, 2, 3, 5];
        arr.pop();//[1,2,3]

 var arr = [1, 2, 3, 5];
        arr.shift();//[2, 3, 5]

   var arr = [1, 2, 3, 5];
        arr.unshift(6);//[6,1,2,3,5]

        //sort  //排序原数组
        //可以自定义排序方式
        //1.必须写两个形参
        //2.看返回值   返回值负数，那么前面的数在后面
        //正数，后面数在前面
        //为0，不动

        var arr = [1, 2, 3, 5, 9, 20, 4, 7, 4];
        arr.sort(function (a, b) {
            return Math.random() - 0.5;
        });

var arr= [1,2,3,5];
        arr.reverse();//[5,3,2,1]

//arr.splice(3,0,4),可以传负数，以下是负数的实现
/splice = function (pos) {
 // pos += pos > 0 ? 0 : this.length;
 //}

       var arr=[1,2,3];
       var arr1=[4,5,6];
       var newarr = arr.concat(arr1);//[1,2,3,4,5,6]

var str="h";
var str1=‘e‘;
var str2="l";
var str3=‘l‘;
var str4=‘o‘;
var arr=[str,str1,str2,str3,str4];
var newarr = arr.join(‘‘)//默认为，传个空字符 hello  //拼接字符串这中效率较高

//字符串方法split  分割成数组
var arr = [‘h‘, ‘e‘, ‘l‘, ‘l‘, ‘o‘];
var str = arr.join(‘-‘);
var newarr = str.split(‘-‘);//["h", "e", "l", "l", "o"]

var arr=[1,2,3];
var newarr = arr.toString();//"1,2,3"

var arr = [1,2,3];
var newarr = arr.slice(1,3);// 2
var newarr1 = arr.splice(0);//[1,2,3]