Remove last comma (and possible whitespaces after the last comma) from the end of a string

This will remove the last comma and any whitespace after it:

str = str.replace(/,\s*$/, "");

It uses a regular expression:

• The / mark the beginning and end of the regular expression

• The , matches the comma

• The \s means whitespace characters (space, tab, etc) and the * means 0 or more

• The $ at the end signifies the end of the string