feat: add isPrime algorithm

Maths/IsPrime.js

@@ -0,0 +1,25 @@
+/**
+ * @function isPrime
+ * @description A prime number is a natural number greater than 1 that has
+ *   no positive divisors other than 1 and itself. This function checks
+ *   whether a given number is prime.
+ * @param {number} n - A positive integer
+ * @returns {boolean} - True if n is prime, false otherwise
+ * @see https://en.wikipedia.org/wiki/Prime_number
+ * @example isPrime(2) => true
+ * @example isPrime(11) => true
+ * @example isPrime(4) => false
+ */
+const isPrime = (n) => {
+  if (!Number.isInteger(n) || n < 2) {
+    throw new TypeError('Input must be an integer greater than or equal to 2')
+  }
+  if (n === 2) return true
+  if (n % 2 === 0) return false
+  for (let i = 3; i <= Math.sqrt(n); i += 2) {
+    if (n % i === 0) return false
+  }
+  return true
+}
+
+export { isPrime }

Maths/test/IsPrime.test.js

@@ -0,0 +1,47 @@
+import { isPrime } from '../IsPrime.js'
+
+describe('isPrime', () => {
+  test('2 is prime', () => {
+    expect(isPrime(2)).toBe(true)
+  })
+
+  test('3 is prime', () => {
+    expect(isPrime(3)).toBe(true)
+  })
+
+  test('4 is NOT prime', () => {
+    expect(isPrime(4)).toBe(false)
+  })
+
+  test('11 is prime', () => {
+    expect(isPrime(11)).toBe(true)
+  })
+
+  test('13 is prime', () => {
+    expect(isPrime(13)).toBe(true)
+  })
+
+  test('25 is NOT prime', () => {
+    expect(isPrime(25)).toBe(false)
+  })
+
+  test('97 is prime', () => {
+    expect(isPrime(97)).toBe(true)
+  })
+
+  test('100 is NOT prime', () => {
+    expect(isPrime(100)).toBe(false)
+  })
+
+  test('throws TypeError for 1', () => {
+    expect(() => isPrime(1)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for negative input', () => {
+    expect(() => isPrime(-7)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for float input', () => {
+    expect(() => isPrime(2.5)).toThrow(TypeError)
+  })
+})