uniqueCount = ["a","b","c","d","d","e","a","b","c","f","g","h","h","h","e","a"]; var count = {}; uniqueCount.forEach(function(i) { count[i] = (count[i]||0) + 1;}); console.log(count);
var counts = {}; your_array.forEach(function(x) { counts[x] = (counts[x] || 0)+1; });