/** * @function countSubstrings * @description Given a string of words or phrases, count the occurrences of a substring * @param {String} str - The input string * @param {String} substring - The substring * @return {Number} - The number of substring occurrences * @example countSubstrings("This is a string", "is") => 2 * @example countSubstrings("Hello", "e") => 1 */ const countSubstrings = (str, substring) => { if (typeof str !== 'string' || typeof substring !== 'string') { throw new TypeError('Argument should be string') } if (substring.length === 0) return str.length + 1 let count = 0 let position = str.indexOf(substring) while (position > -1) { count++ position = str.indexOf(substring, position + 1) } return count } export { countSubstrings }