快排

 var arr = [1,8,9,3,7,5];        function quickSort(obj) {            if (obj.length <= 1) {                return obj;            }            var num = Math.floor(obj.length/2),                numValue = obj.splice(num,1);            var left = [],                right = [];            for (var i = 0; i < obj.length; i++) {                if (obj[i] < numValue) {                    left.push(obj[i]);                } else {                    right.push(obj[i]);                }            }            return quickSort(left).concat(numValue,quickSort(right));        };        console.log(quickSort(arr));