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

    1.join:

                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);

    功能:将数组转换为字符串,与slice相反,对原数组不改变

    结果:

     2.concat:

                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);

    功能:对原数组进行连接操作,并把连接后的返回新数组。原数组不变

    结果:

     3.splice:

                //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);

     4.slice:

    不改变原数组

                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);

     5.indexOf:

    在数组中查找元素,可以根据第二个参数的起始位置开始查找,返回查找元素的下标,如果没找返回-1

    6.lastindexOf

    从后向前搜索,查找到元素的下标返回(返回的下标是按从前往后的下标来)

    7.charCodeAt:

            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

    8.fromcharCodeAt:

           var str = "az";
                console.log(String.fromCharCode(23447))//23447转换为字符
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  • 原文地址:https://www.cnblogs.com/MySweetheart/p/12291421.html
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