diff --git a/String/CheckHeterogram.js b/String/CheckHeterogram.js
new file mode 100644
index 0000000000..624c1ca216
--- /dev/null
+++ b/String/CheckHeterogram.js
@@ -0,0 +1,40 @@
+// A [Heterogram](https://en.wikipedia.org/wiki/Heterogram_(literature)) is a word, phrase or sentence in which no letter of the alphabet occurs more than once.
+
+/**
+ * @function checkHeterogram
+ * @param {string} str
+ * @returns {boolean}
+ * @description - check if a string is a heterogram
+ * @example - checkHeterogram('hero') => true
+ * @example - checkHeterogram('CoMpUtEr') => true
+ * @example - checkHeterogram('Great work!!') => true
+ * @example - checkHeterogram('Aba') => false
+ */
+
+const checkHeterogram = (str) => {
+ // Check that input is a string
+ if (typeof str !== 'string') {
+ throw new TypeError('Argument not a string.')
+ }
+
+ // initialize a hashmap where the letters of the string will be checked for duplicates
+ const letters = new Map()
+
+ // Check all the characters in the string by looping through it
+ for (let i = 0; i < str.length; i++) { + // If the character is a letter check whether it is a duplicate + if (str.charAt(i).match(/[a-z]/gi)) { + // If the letter exists in the hashmap already return false else store it in the hashmap + if (letters.has(str.charAt(i).toLowerCase())) { + return false + } else { + letters.set(str.charAt(i).toLowerCase()) + } + } + } + + // Once all characters of the string have been checked return true + return true +} + +export { checkHeterogram } diff --git a/String/test/CheckHeterogram.test.js b/String/test/CheckHeterogram.test.js new file mode 100644 index 0000000000..4c036c23dc --- /dev/null +++ b/String/test/CheckHeterogram.test.js @@ -0,0 +1,31 @@ +import { checkHeterogram } from '../CheckHeterogram' + +describe('Testing checkHeterogram', () => {
+ it('expects to throw type error if given a non string argument', () => {
+ expect(() => checkHeterogram(0)).toThrow()
+ })
+ it('expects to throw type error if given a non string argument', () => {
+ expect(() => checkHeterogram(true)).toThrow()
+ })
+ it('expects to return true if the argument is a heterogram', () => {
+ expect(checkHeterogram('hero')).toBe(true)
+ })
+ it('expects to return true if the given argument only contains non-alphabetic characters', () => {
+ expect(checkHeterogram('!!..&& ??22')).toBe(true)
+ })
+ it('expects to return true if the given string is a heterogram which contains duplicate non-alphabetic characters', () => {
+ expect(checkHeterogram('C, o, m, p, u, t, e, r!!')).toBe(true)
+ })
+ it('expects to return true if the given string is empty', () => {
+ expect(checkHeterogram('')).toBe(true)
+ })
+ it('expects to return true if the given string contains multiple spaces and is a heterogram', () => {
+ expect(checkHeterogram('Cwm fjord bank glyphs vext quiz')).toBe(true)
+ })
+ it('expects to return false if the given string contains duplicate letters with differing case (case insensitive)', () => {
+ expect(checkHeterogram('Ada')).toBe(false)
+ })
+ it('expects to return false if the given string contains duplicate letters in different words', () => {
+ expect(checkHeterogram('List duplicates')).toBe(false)
+ })
+})
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