js冒泡排序从小到大排列

var str = [4,3,52,2,5,1,8];
for (var i = 0; i <= str.length- 1; i++ ) {
    for (var j = 0; j <= str.length - i -1; j++) {
        if (str[j + 1] < str[j]) {
            var num = str[j];
            str[j] = str[j+1];
            str[j+1] = num;

        }
    }
}
console.log(str);