js笔试题

1.js中数组的操作

（部分操作原数组，部分形成新的数组）

1. pop

		var arr = [1,2,3,4,5];
		arr.pop()//从数组最后删除
		console.log(arr)// [1, 2, 3, 4]

2.push

		var arr = [1,2,3,4,5];
		arr.push(6,7)//在最后添加数据
		console.log(arr)// [1, 2, 3, 4, 5, 6, 7]

3.shift

		var arr = [1,2,3,4,5];
 		arr.shift()//从开头删除
		console.log(arr)//[2, 3, 4, 5]

4.unshift

		var arr = [1,2,3,4,5];
 		arr.unshift(99,100)//从开头加入数据
		console.log(arr)

5.concat

		var arr = [1,2,3,4,5];
 		var arr1 = arr.concat(6,7,8,9,10);//连接2个数组
		console.log(arr1)// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

6.splice

		array.splice(index,howmany,item1,.....,itemX)
		//index:规定从何处添加/删除元素。
		//howmany:规定应该删除多少元素。必须是数字，但可以是 "0"。
		//item1, ..., itemX	可选。要添加到数组的新元素
		var arr = [1,2,3,4,5];
 		var arr1 = arr.splice(2,2,8,9,10);
		console.log(arr)//[1, 2, 8, 9, 10, 5]
		console.log(arr1)//[3, 4]

7.reverse

		var arr = [1,2,3,4,5];
 		arr.reverse();//反转数组数值顺序
		console.log(arr)//[5, 4, 3, 2, 1]

8.slice

		var arr = [1,2,3,4,5];
 		var arr1 = arr.slice(1,4);//从规定位置取出数据
		console.log(arr1)// [2, 3, 4]

9.数组去重

  		var arr = [13,24,34,24,15,46,46,27,34,18,13,39,10];
        var arr1 = [];
        for (var i = 0; i < arr.length; i++) {
           if( arr.indexOf(arr[i])==i)
            {
                arr1.push(arr[i]);
            }
        }
       console.log(arr1);//[13, 24, 34, 15, 46, 27, 18, 39, 10]

2.js中使用typeof能得到哪些类型？

undefined、string、number、boolean、object、function

转载：https://blog.csdn.net/lemon94924/article/details/101349860