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

If you are using lodash, the _.countBy method will do this:

_.countBy("abcda")['a'] //2

This method also work with array:

_.countBy(['ab', 'cd', 'ab'])['ab'] //2