1function count(str, find) {
2    return (str.split(find)).length - 1;
3}
4
5count("Good", "o"); // 2

1function countOccurences(string, word) {
2   return string.split(word).length - 1;
3}
4var text="We went down to the stall, then down to the river."; 
5var count=countOccurences(text,"down"); // 2

1 function countInstancesOf(letter, sentence) {
2  var count = 0;
3
4  for (var i = 0; i < sentence.length; i++) {
5    if (sentence.charAt(i) === letter) {
6      count += 1;
7    }
8  }
9  return count;
10}