数组常见习题

数组去重：

		 var arr = [1, 2, 2, 2, 2, 4, 5, 6, 6, 6, 6, 8, 8, 9, 9, 99]
		 var res = [];
		 for (var i = 0; i < arr.length; i++) {
		       if(res.indexOf(arr[i]) == -1) {
		           res.push(arr[i]);  
		        }
		  }
		 console.log(res);

输出数组中最大值：

        var arr = [12,3,44,34,56,777,56]
        var max = arr[0]
        for(var i = 0;i < arr.length;i++){
            if(arr[i] > max){
                max = arr[i]
            }
        }
        console.log(max);

合并数组并去重：

        var arr = [2,3,4,555,6,7,6,2,3,4]
        var arr2 = ['a','b','c','d','a','b','c']
        var res = arr.concat(arr2)
        var res2 = [];
        for(var i = 0;i < res.length;i++){
            if(res2.indexOf(res[i]) == -1){
                res2.push(res[i])
            }
        }
        console.log(res2);

数组排序 【升序】

    var arr = [1, 22, 3, 4, 5, 45, 32]
    arr.sort(function (a, b) {
         return a - b;
     });
    console.log(arr);

数组排序 【降序】

     var arr = [33, 2, 1, 4, 45, 23]
     arr.sort(function (a, b) {
         return b - a;
     });
     console.log(arr);