feat: added isolateDecimal

maths/decimal_isolation.ts

@@ -0,0 +1,23 @@
+/**
+ * @function isolateDecimal
+ * @description Isolate the decimal part of a number.
+ * @param {number} num - The number to isolate the decimal part from.
+ * @returns {Object} - Object containing the integral part and the decimal part.
+ * @throws {TypeError} - when the input is not a number.
+ * @example isolateDecimal(3.14) => { integralPart: 3, decimalPart: 0.14 }
+ */
+
+export const isolateDecimal = (
+  num: number
+): { integralPart: number; decimalPart: number } => {
+  if (typeof num !== 'number') {
+    throw new TypeError('Input must be a number')
+  }
+
+  num = Math.abs(num)
+
+  const integralPart = Math.trunc(num)
+  const decimalPart = num - integralPart
+
+  return { integralPart, decimalPart: Number(decimalPart.toFixed(10)) }
+}

maths/test/decimal_isolation.test.ts

@@ -0,0 +1,16 @@
+import { isolateDecimal } from '../decimal_isolation'
+
+describe('isolateDecimal', () => {
+  test('isolate the decimal part of a number', () => {
+    expect(isolateDecimal(3.14)).toEqual({ integralPart: 3, decimalPart: 0.14 })
+    expect(isolateDecimal(0.14)).toEqual({ integralPart: 0, decimalPart: 0.14 })
+    expect(isolateDecimal(-3.14)).toEqual({
+      integralPart: 3,
+      decimalPart: 0.14
+    })
+  })
+
+  test('throws an error when the input is not a number', () => {
+    expect(() => isolateDecimal('3.14' as unknown as number)).toThrow(TypeError)
+  })
+})