When I want to sort an array, using sort() function , it is giving an alphabetically sorted array. Eg.
var a=[9,10,1];
a.sort();
I'm getting a = [1,10,9]
So, as per the suggestions I used another function
function sortfunction(x, y){
return (x - y) //causes an array to be sorted numerically and ascending
}
and then used
a.sort(sortfunction);
to get the right result.
Can anyone explain in detail, how this works?
The first version fails as they're compared like they're strings ("9" is greater than "10"), known as a lexicographic sort.
The custom comparator function is called with a and b being members of the array.
Depending on what is returned, the members are shifted. If 0 is returned, the members are considered equivalent, if a negative number, then a is less than b and the inverse if it's a positive number.
If you want to visualise this, you can always log a and b to the console and observe how they're compared (and note how there is never any redundant comparisons made).
This is all backed by a sorting algorithm, which is left up to the implementation to choose. Chrome, for example, uses different algorithms depending on the type of members.
x - y will always be true if x and y are not the same?
x - y ever true if they're numbers?
.sort depends on negative or positive values. I thought it receives a Boolean instead. I totally forgot about it and I just read the spec.