用JS实现的常见几种排序算法

1.快速排序法

1. /*快速排序法*/
2. function quickSort(a) {
3. if (a.length <= 1) {
4. return a;
5. }
6. var midLength = Math.floor(a.length / 2);
7. var midValue = a.splice(midLength,1);
8. var left = [];
9. var right = [];
10. for (var i = 0; i < a.length; i++) {
11. if (a[i] < midValue) {
12. left.push(a[i]);
13. } else {
14. right.push(a[i]);
15. }
16. }
17. return quickSort(left).concat(midValue,quickSort(right));
18. }
19. console.log(quickSort([1,5,3,6,2,4,0]));

2.冒泡排序

1. /*冒泡排序法*/
2. function bubbleSort(a) {
3. var length = a.length;
4. var sortArray;
5. for (var i = 0; i < length-1; i++) {
6. for (var j = 0; j < length-i-1 ; j++) {
7. if (a[j] > a[j+1]) {
8. sortArray = a[j];
9. a[j] = a[j+1];
10. a[j+1] = sortArray;
11. }
12. }
13. }
14. return a;
15. }
16. console.log(bubbleSort([2,1,3,6,5,4,7,0]));

3.插入排序

1. /*插入排序法*/
2. function insertSort(a) {
3. var length = a.length;
4. var sortArray;
5. for (var i = 1; i < length; i++) {
6. for (var j = 0; j < i ; j++) {
7. if (a[i] < a[j]) {
8. sortArray = a[i];
9. a[i] = a[j];
10. a[j] = sortArray;
11. }
12. }
13. }
14. return a;
15. }
16. console.log(insertSort([0,6,5,3,4,2,1,7]));

4.选择排序

1. /*选择排序法*/
2. function selectSort(a) {
3. for (var i = 0; i < a.length; i++) {
4. var min = a[i];
5. var k = i;
6. for (var j = i + 1; j < a.length; j++) {
7. if (min > a[j]) {
8. min = a[j];
9. k = j;
10. }
11. }
12. a[k] = a[i];
13. a[i] = min;
14. }
15. return a;
16. }
17. console.log(selectSort([5,1,4,0,3,2,7,6]));

附加：js判断滚动条是否到底部

<style>
*{
padding:0;
margin:0;
}
.test{
position: fixed;
left: 0;
top: 0;
right: 0;
bottom: 0;
width: 600px;
height: 300px;
padding: 20px;
margin: auto;
overflow-y: auto;
border:2px solid #DDD;
}
</style>
<div class="test" id="test">
<p style="height:400%"></p>
</div>
<script>
var test = document.getElementById("test");
test.addEventListener("scroll", function(){
var str = "可滚动距离："+ test.scrollHeight +" 滚动位置："+ test.scrollTop + " 滚动容器高度："+ test.clientHeight;
var p = document.createElement("p");
p.innerHTML = str;
document.body.appendChild(p);
}, false);
</script>