About the Javascript sort () function

I encountered a problem today.

VaR arr = [3, 1, 16, 34, 7, 8];

Arr. Sort ();

The returned result is [,]. It is different from what I want to achieve.

I have read the interface description.

Arrayobject. Sort (sortby ).

Sortby must be a function.

If no parameter is used when this method is called, the elements in the array are sorted alphabetically. More precise, the elements are sorted by character encoding. To achieve this, first convert the elements of the array into strings (if necessary) for comparison.

If you want to sort by other criteria, you need to provide a comparison function that compares two values and returns a number indicating the relative sequence of the two values. The comparison function should have two parameters, A and B. The returned values are as follows:

If a is less than B, A should appear before B in the sorted array, then a value smaller than 0 is returned.

If a is equal to B, 0 is returned.

If a is greater than B, a value greater than 0 is returned.

After reading it, use a function to try it out.

Ascending

Function ascend (a, B ){

Return A-B;

}

Descending Order

Function DESC (a, B ){

Return B-;

}

After testing, there is no problem in ascending order of arr. Sort (ascend) and descending order of arr. Sort (DESC.