CheckAnagram.js

// An [Anagram](https://en.wikipedia.org/wiki/Anagram) is a string that is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once. Anagram check is not case-sensitive;
/**
 * @function checkAnagramRegex
 * @param {string} str1
 * @param {string} str2
 * @returns {boolean}
 * @description - check anagram with the help of Regex
 * @example - checkAnagramRegex('node', 'deno') => true
 * @example - checkAnagramRegex('Eleven plus two', 'Twelve plus one') => true
 */
const checkAnagramRegex = (str1, str2) => {
 // check that inputs are strings.
 if (typeof str1 !== 'string' || typeof str2 !== 'string') {
 throw new TypeError('Both arguments should be strings.')
 }

 // If both strings have not same lengths then they can not be anagram.
 if (str1.length !== str2.length) {
 return false
 }

 /**
 * str1 converted to an array and traverse each letter of str1 by reduce method
 * reduce method return string which is empty or not.
 */
 return ![...str1].reduce(
 (str2Acc, cur) => str2Acc.replace(new RegExp(cur, 'i'), ''), // remove the similar letter from str2Acc in case-insensitive
 str2
 )
}

/**
 * @function checkAnagramMap
 * @description - check anagram via using HashMap
 * @param {string} str1
 * @param {string} str2
 * @returns {boolean}
 * @example - checkAnagramMap('node', 'deno') => true
 * @example - checkAnagramMap('Eleven plus two', 'Twelve plus one') => true
 */
const checkAnagramMap = (str1, str2) => {
 // check that inputs are strings.
 if (typeof str1 !== 'string' || typeof str2 !== 'string') {
 throw new TypeError('Both arguments should be strings.')
 }

 // If both strings have not same lengths then they can not be anagram.
 if (str1.length !== str2.length) {
 return false
 }

 const str1List = Array.from(str1.toUpperCase()) // str1 to array

 // get the occurrences of str1 characters by using HashMap
 const str1Occurs = str1List.reduce(
 (map, char) => map.set(char, map.get(char) + 1 || 1),
 new Map()
 )

 for (const char of str2.toUpperCase()) {
 // if char has not exist to the map it's return false
 if (!str1Occurs.has(char)) {
 return false
 }

 let getCharCount = str1Occurs.get(char)
 str1Occurs.set(char, --getCharCount)

 getCharCount === 0 && str1Occurs.delete(char)
 }

 return true
}

export { checkAnagramRegex, checkAnagramMap }