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.

how to count specific letters in string js

console.log(("str1,str2,str3,str4".match(/,/g) || []).length); //logs 3

console.log(("str1,str2,str3,str4".match(new RegExp("str", "g")) || []).length); //logs 4

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

Javascript count instances of character in a string

 function countInstancesOf(letter, sentence) {
  var count = 0;

  for (var i = 0; i < sentence.length; i++) {
    if (sentence.charAt(i) === letter) {
      count += 1;
    }
  }
  return count;
}