JAVASCRIPT

javascript count occurrences of letter in string

function count(str, find) {
    return (str.split(find)).length - 1;
}

count("Good", "o"); // 2

count occurrences of character in string javascript

var temp = "This is a string.";
var count = (temp.match(/is/g) || []).length;
console.log(count);

Output: 2

Explaination : The g in the regular expression (short for global) says to search the whole string rather than just find the first occurrence. This matches 'is' twice.

javascript count occurence of character in string

// String Prototype: myCount = myString.polycount("countThis")
String.prototype.polycount = function (criteria) {
  return this.split(criteria).length - 1 }
// Arrow Function (STR): myCount = strCount(myString, "countThis")
const strCount = (stack, find) => stack.split(find).length - 1
// Array Prototype: myCount = myArray.polycount("countThis")
Array.prototype.polycount = function (criteria) {
  return this.join("").split(criteria).length - 1 }
// Arrow Function (ARR): myCount = arrCount(myArray, "countThis")
const arrCount = (stack, find) => stack.join("").split(find).length - 1