regex - remove unwanted commas in JavaScript

Question

I want to remove all unnecessary commas from the start/end of the string.

eg; google, yahoo,, , should become google, yahoo.

If possible ,google,, , yahoo,, , should become google,yahoo.

I've tried the below code as a starting point, but it seems to be not working as desired.

trimCommas = function(s) {
 s = s.replace(/,*$/, "");
 s = s.replace(/^,*/, "");
 return s;
}

Answer 1

In your example you also want to trim the commas if there's spaces between them at the start or at the end, use something like this:

str.replace(/^[,s]+|[,s]+$/g, '').replace(/,[,s]*,/g, ',');

Note the use of the 'g' modifier for global replace.