arr = [1,2,3,4]
key = 3
我们要根据key的值来找到这个元素，然后把它挪到数组的第一位，让它返回的结果为[3,1,2,4]
for (var i = 0i <arr.lengthi++) {if (arr[i] === key) { arr.splice(i, 1) break}}arr.unshift(key)
写个swap函数交换不久行了。function swap(arr,i,j) {
if(!arr instanceof Array || arr[i]==undefined || arr[j] ==undefined) {
return
}
var temp = arr[i]
arr[i]=arr[j]
arr[j]=temp
}
<html><script type="text/javascript">
var arr=[1,2,3,4,5,6],t,pos1=1,pos2=4
t=arr[pos1]
arr[pos1]=arr[pos2]
arr[pos2]=t
for(var i=0i<arr.lengthi++)
{
document.write(""+arr[i]+"<br />")
}
</script>
</html>
