Store number of char occurrences in a string

gistfile1.js

function countLetters(string) {

var splitString = string.split('');
var store = {};

  splitString.forEach(function(val, index){
    if (val in store && val !== ' ') {
      store[val]++;
    } else {
      store[val] = 1;
    }
  })

console.log(store);

}

countLetters("hello, here is a string");