Add max word algorithm

String/MaxWord.js

@@ -0,0 +1,36 @@
+// Given a sentence, return the most occuring word
+
+/**
+ * @param {string} sentence - the sentence you want to find the most occuring word
+ * @returns {string} - the most occuring word
+ *
+ * @example
+ *     -  maxWord('lala lili lala'); // lala
+ */
+const maxWord = (sentence = '') => {
+  if (typeof sentence !== 'string') {
+    throw new TypeError('the param sould be string')
+  }
+
+  if (!sentence) {
+    return null
+  }
+
+  const words = sentence.split(' ')
+  if (words.length < 2) {
+    return words[0]
+  }
+
+  const occurrences = {}
+  words.forEach(word => {
+    occurrences[word.toLocaleLowerCase()] = occurrences[word.toLocaleLowerCase()] + 1 || 1
+  })
+
+  const max = Object.keys(occurrences).reduce((n, word) => {
+    if (occurrences[word] > n.count) { return { word, count: occurrences[word] } } else { return n }
+  }, { word: '', count: 0 })
+
+  return max.word
+}
+
+export { maxWord }

String/test/MaxWord.test.js

@@ -0,0 +1,12 @@
+import { maxWord } from '../MaxWord'
+
+describe('Testing the maxWord function', () => {
+  it('Expect throw with non string argument', () => {
+    expect(() => maxWord(10)).toThrow()
+  })
+  it('get the max word', () => {
+    const string = 'ba ba ba ba banana'
+    const mostOccuringWord = maxWord(string)
+    expect(mostOccuringWord).toBe('ba')
+  })
+})