feat: add binary to decimal conversion

Conversions/BinaryToDecimal.js

@@ -1,8 +1,24 @@
-export default function binaryToDecimal(binaryString) {
-  let decimalNumber = 0
-  const binaryDigits = binaryString.split('').reverse() // Splits the binary number into reversed single digits
-  binaryDigits.forEach((binaryDigit, index) => {
-    decimalNumber += binaryDigit * Math.pow(2, index) // Summation of all the decimal converted digits
-  })
-  return decimalNumber
+/**
+ * @function binaryToDecimal
+ * @description Converts a binary number (base-2) string to its decimal
+ *   (base-10) equivalent without using JavaScript's built-in parseInt.
+ * @param {string} binary - A string representing a binary number
+ * @returns {number} - The decimal equivalent of the binary number
+ * @see https://en.wikipedia.org/wiki/Binary_number
+ * @example binaryToDecimal("1010") => 10
+ * @example binaryToDecimal("1111") => 15
+ * @example binaryToDecimal("0") => 0
+ */
+const binaryToDecimal = (binary) => {
+  if (typeof binary !== 'string' || !/^[01]+$/.test(binary)) {
+    throw new TypeError(
+      'Input must be a binary string containing only 0s and 1s'
+    )
+  }
+  return binary
+    .split('')
+    .reverse()
+    .reduce((acc, bit, index) => acc + Number(bit) * Math.pow(2, index), 0)
 }
+
+export { binaryToDecimal }

Conversions/test/BinaryToDecimal.test.js

@@ -1,15 +1,39 @@
-import binaryToDecimal from '../BinaryToDecimal'
+import { binaryToDecimal } from '../BinaryToDecimal.js'
 
-describe('BinaryToDecimal', () => {
-  it('expects to return correct decimal value', () => {
-    expect(binaryToDecimal('1000')).toBe(8)
+describe('binaryToDecimal', () => {
+  test("binaryToDecimal('0') returns 0", () => {
+    expect(binaryToDecimal('0')).toBe(0)
   })
 
-  it('expects to return correct hexadecimal value for more than one hex digit', () => {
-    expect(binaryToDecimal('01101000')).toBe(104)
+  test("binaryToDecimal('1') returns 1", () => {
+    expect(binaryToDecimal('1')).toBe(1)
   })
 
-  it('expects to return correct hexadecimal value for padding-required binary', () => {
-    expect(binaryToDecimal('1000101')).toBe(69)
+  test("binaryToDecimal('1010') returns 10", () => {
+    expect(binaryToDecimal('1010')).toBe(10)
+  })
+
+  test("binaryToDecimal('1111') returns 15", () => {
+    expect(binaryToDecimal('1111')).toBe(15)
+  })
+
+  test("binaryToDecimal('100000') returns 32", () => {
+    expect(binaryToDecimal('100000')).toBe(32)
+  })
+
+  test("binaryToDecimal('11111111') returns 255", () => {
+    expect(binaryToDecimal('11111111')).toBe(255)
+  })
+
+  test('throws TypeError for non-binary string', () => {
+    expect(() => binaryToDecimal('1012')).toThrow(TypeError)
+  })
+
+  test('throws TypeError for empty string', () => {
+    expect(() => binaryToDecimal('')).toThrow(TypeError)
+  })
+
+  test('throws TypeError for non-string input', () => {
+    expect(() => binaryToDecimal(1010)).toThrow(TypeError)
   })
 })