// program to check the occurrence of a character
function countString(str, letter) {
// creating regex
const re = new RegExp(letter, 'g');
// matching the pattern
const count = str.match(re).length;
return count;
}
// take input from the user
const string = prompt('Enter a string: ');
const letterToCheck = prompt('Enter a letter to check: ');
//passing parameters and calling the function
const result = countString(string, letterToCheck);
// displaying the result
console.log(result);