js冒泡排序

<script>
//冒泡排序
window.onload = fun;//赋值
function fun() {
var attr = [10, 2, 3, 1, 19, 30], num;
for (var i = 0; i < attr.length - 1; i++) {
for (var j = 0; j < attr.length - i - 1; j++) {
if (attr[j] < attr[j + 1]) {
num = attr[j];
attr[j] = attr[j + 1];
attr[j + 1] = num;
}
}
}
for (var i in attr) {
document.write(attr[i] + " ");
}
}
</script>