Characters Map in JavaScript

charactermap.js

//specs
const str = 'nice to meet you!';
buildCharMap(str); // {"n":1,"i":1,"c":1,"e":3," ":3,"t":2,"o":2,"m":1,"y":1,"u":1,"!":1}

function buildCharMap(str) {
  const char = {};
  for(let character of str) {
    char[character] = char[character] && char[character] + 1 || 1;
  }
  return char;
}