join&concat&splice&slice&indexOf&lastindexOf&charCodeAt&fromCharCode

            var arr=[1,2,3,4];
            arr.join("");
            console.log(arr);
            var s = arr.join("#");//设置一个符号，用这个符号连接数组的每个元素
            console.log(s);

            var arr2 = [2,4,5,6];
            arr2.concat([5,6]);
            console.log(arr2);
            var arr1=arr2.concat();//没有参数时，是复制数组
            console.log(arr1);
            var arr3=arr2.concat([5,6,7,8]);//将5,6,7,8连接到arr2
            console.log(arr3);

            //不执行操作
            var ar0 = [1,2,3,4,5];
            ar0.splice();
            console.log(ar0);

            //创建一个新空数组返回
            var arr=[1,2,3,4,5];
            var arr1 = arr.splice();
            console.log(arr1);

            //负数即从后往前删，即-1到-3（倒着来的最右边下标为0然后往左直到2）
            var ar =[1,2,3,4,5];
            ar.splice(-3);
            console.log(ar);

            //正着来从下标为3开始删包括下标为3
            var ar1 =[1,2,3,4,5];
            ar1.splice(3);
            console.log(ar1);

            //返回删除的值
            var ar2=[1,2,3,4,5];
            var arr3 =ar2.splice(-3);
            console.log(arr3,ar2);

            //清空数组
            var ar3 =[1,2,3,4,5];
            ar3.splice(0);
            console.log(ar3);

            //将ar3所有元素导入到arr2中，
            var ar3 =[1,2,3,4,5];
            var arr2 =ar3.splice(0);//并且清空ar3
            console.log(arr2,ar3);

            //删除下标从0-2不包括2
            var ar4 = [1,2,3,4,5];
            ar4.splice(0,2);
            console.log(ar4);

            //从下标为3开始删除两位即下标为3,4
            var ar5 =[1,2,3,4,5,6];
            ar5.splice(3,2);
            console.log(ar5);

            //从右边往左边删3个,后面那个数大小无所谓，没影响
            var ar6 =[1,2,3,4,87,7,18,20];
            ar6.splice(-3,9);
            console.log(ar6);

            //没有任何删除操作
            var ar7 =[1,2,3,4,87,7,18,20];
             ar7.splice(4,-2);
            console.log(ar7);
            //没有任何删除操作
            var ar8 = [1,2,3,4,20];
            ar8.splice(-4,-5);
            console.log(ar8);

            //删除下标0-5的,原数组由9开头
            var ar9 =[1,2,3,4,7,8,98];
            var arr4 = ar9.splice(0,5,9);
            console.log(ar9);
            console.log(arr4);

            //删除下标为5后面的两个数，并且把11插在原数组后面
            var ar10 =[1,2,3,4,7,8,98];
            var arr5 =ar10.splice(5,2,11);
            console.log(ar10);
            console.log(arr5);

            //只要中间小于等于0且第一位大于第二位时，在下标为2处插入99
            var ar11 = [9,4,1,6,9,89];
            var arr6 = ar11.splice(2,0,99);
            console.log(arr6);
            console.log(ar11);

            //删除倒数第一位，并且插入110,中间数多少无所谓
            var ar12 =[9,6,4,3,98];
            var arr7 = ar12.splice(-1,0,110);
            console.log(ar12);
            console.log(arr7);

            //从第一位开始替换两个元素为-1，-2,并将替换的值返回给新数组
            var ar13 =[3,8,5,14,6];
            var arr8 =ar13.splice(1,2,-1,-2);
            console.log(ar13);
            console.log(arr8);

            var arr = [1,24,4,2,1,4,5,2,5,6,7,7];
            arr.slice(0,2);
            console.log(arr);

            //删除下标1-4，不包括4
            var arr = [1,24,4,2,1,4,5,2,5,6,7,7];
            var arr1= arr.slice(1,4);
            console.log(arr1);

 　　　　　　　var str = "az";
            str.charCodeAt(0);//把下标为0的字符串a拿出来，并返回a的值为97

　　　　　　　var str = "az";
            console.log(String.fromCharCode(23447))//将23447转换为字符