Count the number of occurrences of a character in a string in Javascript

Question

I need to count the number of occurrences of a character in a string.

For example, suppose my string contains:

var mainStr = \"str1,str2,str3,str4\";         


        

Answer 1

ok, an other one with regexp - probably not fast, but short and better readable then others, in my case just '_' to count

key.replace(/[^_]/g,'').length

just remove everything that does not look like your char but it does not look nice with a string as input