常用排序方法 —— JavaScript 实现

一、冒泡排序

	function bubbleSort(arr) {
	    var len = arr.length;
	    var temp;
	    for (var i = 0; i < len; i++) {
	        for (var j = 0; j < len - 1 - i; j++) {
	            if (arr[j] > arr[j+1]) {     
	                temp = arr[j+1];        
	                arr[j+1] = arr[j];
	                arr[j] = temp;
	            }
	        }
	    }
	    return arr;
	}

二、选择排序

	function selectionSort(arr) {
	    var len = arr.length;
	    var min, temp;
	    for (var i = 0; i < len - 1; i++) {
	        min = arr[i];
	        for (var j = i + 1; j < len; j++) {
	            if (arr[j] < min) {     //寻找最小的数
	                min = arr[j];                 //将最小数的索引保存
	            }
	        }
	        temp = arr[i];
	        arr[i] = arr[minIndex];
	        arr[minIndex] = temp;
	    }
	    return arr;
	}

三、插入排序

	function insertionSort(arr) {
	    var len = arr.length;
	    var preIndex, current;
	    for (var i = 1; i < len; i++) {
	        preIndex = i - 1;
	        current = arr[i];
	        while(preIndex >= 0 && arr[preIndex] > current) {
	            arr[preIndex+1] = arr[preIndex];
	            preIndex--;
	        }
	        arr[preIndex+1] = current;
	    }
	    return arr;
	}

四、快速排序

	function quickSort(arr, left, right) {
	    var len = arr.length,
	        partitionIndex;
	    if (left < right) {
	        partitionIndex = partition(arr, left, right);
	        quickSort(arr, left, partitionIndex-1);
	        quickSort(arr, partitionIndex+1, right);
	    }
	    return arr;
	}
	
	function partition(arr, left ,right) {     //分区操作
	    var pivot = left,                      //设定基准值（pivot）
	        index = pivot + 1;
	    for (var i = index; i <= right; i++) {
	        if (arr[i] < arr[pivot]) {
	            swap(arr, i, index);
	            index++;
	        }       
	    }
	    swap(arr, pivot, index - 1);
	    return index-1;
	}
	
	function swap(arr, i, j) {
	    var temp = arr[i];
	    arr[i] = arr[j];
	    arr[j] = temp;
	}