diff --git a/String/CheckAnagram.js b/String/CheckAnagram.js
index 21ca1458d..1fc585429 100644
--- a/String/CheckAnagram.js
+++ b/String/CheckAnagram.js
@@ -1,10 +1,17 @@
-// 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 case sensitive; i.e. Aba and aba is not a anagram.
-// inputs are strings i.e. str1 and str2
-const checkAnagram = (str1, str2) => {
+// 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') {
-    return 'Not string(s)'
+    throw new TypeError('Both arguments should be strings.')
   }
 
   // If both strings have not same lengths then they can not be anagram.
@@ -12,36 +19,58 @@ const checkAnagram = (str1, str2) => {
     return false
   }
 
-  // Use hashmap to keep count of characters in str1
+  /**
+   * str1 converted to an array and traverse each letter of str1 by reduce method
+   * reduce method return string which is empty or not.
+   * if it returns empty string '' -> falsy, with Logical !(NOT) Operator, it's will be converted to boolean and return true else false
+   */
+  return ![...str1].reduce(
+    (str2Acc, cur) => str2Acc.replace(new RegExp(cur, 'i'), ''), // remove the similar letter from str2Acc in case-insensitive
+    str2
+  )
+}
 
-  const str1CharCount = new Map()
+/**
+ * @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.')
+  }
 
-  for (let i = 0; i < str1.length; i++) {
-    let previousCount = 0
-    if (str1CharCount.has(str1[i])) {
-      previousCount = str1CharCount.get(str1[i])
+  // 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
     }
-    str1CharCount.set(str1[i], previousCount + 1)
-  }
 
-  // Now check if second string has same characters?
+    let getCharCount = str1Occurs.get(char)
+    str1Occurs.set(char, --getCharCount)
 
-  for (let i = 0; i < str2.length; i++) {
-    let previousCount = 0
-    // if str1CharCount has no key for str2[i] then not anagram.
-    if (!str1CharCount.has(str2[i])) return false
-
-    previousCount = str1CharCount.get(str2[i])
-    str1CharCount.set(str2[i], previousCount - 1)
-  }
-
-  // Now check if all entries in hashmap has zeros.
-
-  for (const key in str1CharCount) {
-    if (str1CharCount[key] !== 0) return false
+    getCharCount === 0 && str1Occurs.delete(char)
   }
 
   return true
 }
 
-export { checkAnagram }
+export { checkAnagramRegex, checkAnagramMap }
diff --git a/String/test/CheckAnagram.test.js b/String/test/CheckAnagram.test.js
index ae1a3a593..44adc196b 100644
--- a/String/test/CheckAnagram.test.js
+++ b/String/test/CheckAnagram.test.js
@@ -1,6 +1,6 @@
-import { checkAnagram } from '../CheckAnagram'
+import { checkAnagramMap, checkAnagramRegex } from '../CheckAnagram'
 
-describe('checkAnagram', () => {
+describe('Testing checkAnagramRegex', () => {
   it.each`
     inputOne              | inputTwo
     ${123456}             | ${'abcd'}
@@ -10,79 +10,172 @@ describe('checkAnagram', () => {
     ${'abcd'}             | ${[1, 2, 3, 4, 5, 6]}
     ${'abcd'}             | ${{ test: 'test' }}
   `(
-    'expects to return "Not string(s)" given values $inputOne and $inputTwo',
+    'expects to throw the type Error given values $inputOne and $inputTwo',
     ({ inputOne, inputTwo }) => {
-      const SUT = checkAnagram(inputOne, inputTwo)
-      expect(SUT).toBe('Not string(s)')
+      expect(
+        () => checkAnagramRegex(inputOne, inputTwo)
+      ).toThrowError()
     }
   )
 
   it('expects to return false if the arguments have different lengths', () => {
-    const SUT = checkAnagram('abs', 'abds')
+    const SUT = checkAnagramRegex('abs', 'abds')
     expect(SUT).toBe(false)
   })
 
   it('expects to return false if the arguments are not anagrams', () => {
-    const SUT = checkAnagram('abcs', 'abds')
+    const SUT = checkAnagramRegex('abcs', 'abds')
     expect(SUT).toBe(false)
   })
 
   it('expects to return true if the arguments are anagrams', () => {
-    const SUT = checkAnagram('abcd', 'bcad')
+    const SUT = checkAnagramRegex('abcd', 'bcad')
     expect(SUT).toBe(true)
   })
 
   it('expects to return true if the arguments of length 1 and are the same letter', () => {
-    const SUT = checkAnagram('a', 'a')
+    const SUT = checkAnagramRegex('a', 'a')
     expect(SUT).toBe(true)
   })
 
   it('expects to return true if the arguments of are both empty strings', () => {
-    const SUT = checkAnagram('', '')
+    const SUT = checkAnagramRegex('', '')
     expect(SUT).toBe(true)
   })
 
   it('expects to return true if the arguments are anagrams with an odd length', () => {
-    const SUT = checkAnagram('abcde', 'edcab')
+    const SUT = checkAnagramRegex('abcde', 'edcab')
     expect(SUT).toBe(true)
   })
 
   it('expects to return true if the arguments are anagrams with an even length', () => {
-    const SUT = checkAnagram('abcdef', 'fedcab')
+    const SUT = checkAnagramRegex('abcdef', 'fedcab')
     expect(SUT).toBe(true)
   })
 
   it('expects to return false if either argument is an empty string while the other is not', () => {
-    const SUT = checkAnagram('', 'edcab')
+    const SUT = checkAnagramRegex('', 'edcab')
     expect(SUT).toBe(false)
-    const SUT2 = checkAnagram('edcab', '')
+    const SUT2 = checkAnagramRegex('edcab', '')
     expect(SUT2).toBe(false)
   })
 
-  it('expects to return false if the arguments contain the same letters but have unequal case', () => {
-    const SUT = checkAnagram('ABDCE', 'abcde')
-    expect(SUT).toBe(false)
-    const SUT2 = checkAnagram('AbCdE', 'aBCdE')
-    expect(SUT2).toBe(false)
+  it('expects to return true if the arguments contain the same letters but have unequal case', () => {
+    const SUT = checkAnagramRegex('ABDCE', 'abcde')
+    expect(SUT).toBe(true)
+    const SUT2 = checkAnagramRegex('AbCdE', 'aBCdE')
+    expect(SUT2).toBe(true)
+    const SUT3 = checkAnagramRegex('Eleven plus two', 'Twelve plus one')
+    expect(SUT3).toBe(true)
   })
 
   it('expects to return true if the arguments are anagrams and contain number characters', () => {
-    const SUT = checkAnagram('a1b2', '12ba')
+    const SUT = checkAnagramRegex('a1b2', '12ba')
     expect(SUT).toBe(true)
   })
 
   it('expects to return true if the arguments are anagrams and contain space characters', () => {
-    const SUT = checkAnagram('a1 b2', '1 2ba')
+    const SUT = checkAnagramRegex('a1 b2', '1 2ba')
     expect(SUT).toBe(true)
   })
 
   it('expects to return true if the arguments are anagrams and contain punctuation characters', () => {
-    const SUT = checkAnagram('a!1b@2', '1@2ba!')
+    const SUT = checkAnagramRegex('a!1b@2', '1@2ba!')
     expect(SUT).toBe(true)
   })
 
   it('expects to return false if the arguments contain the same letters but contain a different amount of space characters', () => {
-    const SUT = checkAnagram('ea        cb', 'e cba')
+    const SUT = checkAnagramRegex('ea        cb', 'e cba')
+    expect(SUT).toBe(false)
+  })
+})
+
+describe('Testing checkAnagramMap', () => {
+  it.each`
+    inputOne              | inputTwo
+    ${123456}             | ${'abcd'}
+    ${[1, 2, 3, 4, 5, 6]} | ${'abcd'}
+    ${{ test: 'test' }}   | ${'abcd'}
+    ${'abcd'}             | ${123456}
+    ${'abcd'}             | ${[1, 2, 3, 4, 5, 6]}
+    ${'abcd'}             | ${{ test: 'test' }}
+  `(
+    'expects to throw the type Error given values $inputOne and $inputTwo',
+    ({ inputOne, inputTwo }) => {
+      expect(
+        () => checkAnagramMap(inputOne, inputTwo)
+      ).toThrowError()
+    }
+  )
+
+  it('expects to return false if the arguments have different lengths', () => {
+    const SUT = checkAnagramMap('abs', 'abds')
+    expect(SUT).toBe(false)
+  })
+
+  it('expects to return false if the arguments are not anagrams', () => {
+    const SUT = checkAnagramMap('abcs', 'abds')
+    expect(SUT).toBe(false)
+  })
+
+  it('expects to return true if the arguments are anagrams', () => {
+    const SUT = checkAnagramMap('abcd', 'bcad')
+    expect(SUT).toBe(true)
+  })
+
+  it('expects to return true if the arguments of length 1 and are the same letter', () => {
+    const SUT = checkAnagramMap('a', 'a')
+    expect(SUT).toBe(true)
+  })
+
+  it('expects to return true if the arguments of are both empty strings', () => {
+    const SUT = checkAnagramMap('', '')
+    expect(SUT).toBe(true)
+  })
+
+  it('expects to return true if the arguments are anagrams with an odd length', () => {
+    const SUT = checkAnagramMap('abcde', 'edcab')
+    expect(SUT).toBe(true)
+  })
+
+  it('expects to return true if the arguments are anagrams with an even length', () => {
+    const SUT = checkAnagramMap('abcdef', 'fedcab')
+    expect(SUT).toBe(true)
+  })
+
+  it('expects to return false if either argument is an empty string while the other is not', () => {
+    const SUT = checkAnagramMap('', 'edcab')
+    expect(SUT).toBe(false)
+    const SUT2 = checkAnagramMap('edcab', '')
+    expect(SUT2).toBe(false)
+  })
+
+  it('expects to return true if the arguments contain the same letters but have unequal case', () => {
+    const SUT = checkAnagramMap('ABDCE', 'abcde')
+    expect(SUT).toBe(true)
+    const SUT2 = checkAnagramMap('AbCdE', 'aBCdE')
+    expect(SUT2).toBe(true)
+    const SUT3 = checkAnagramMap('Eleven plus two', 'Twelve plus one')
+    expect(SUT3).toBe(true)
+  })
+
+  it('expects to return true if the arguments are anagrams and contain number characters', () => {
+    const SUT = checkAnagramMap('a1b2', '12ba')
+    expect(SUT).toBe(true)
+  })
+
+  it('expects to return true if the arguments are anagrams and contain space characters', () => {
+    const SUT = checkAnagramMap('a1 b2', '1 2ba')
+    expect(SUT).toBe(true)
+  })
+
+  it('expects to return true if the arguments are anagrams and contain punctuation characters', () => {
+    const SUT = checkAnagramMap('a!1b@2', '1@2ba!')
+    expect(SUT).toBe(true)
+  })
+
+  it('expects to return false if the arguments contain the same letters but contain a different amount of space characters', () => {
+    const SUT = checkAnagramMap('ea        cb', 'e cba')
     expect(SUT).toBe(false)
   })
 })