feat: add string isNumeric algorithm

String/IsNumeric.js

@@ -0,0 +1,21 @@
+/**
+ * @function isNumeric
+ * @description Checks whether a string represents a valid numeric value.
+ *   Supports integers, floats, and negative numbers.
+ * @param {string} str - The input string to check
+ * @returns {boolean} - True if the string is numeric, false otherwise
+ * @see https://en.wikipedia.org/wiki/Numeric_string
+ * @example isNumeric("123") => true
+ * @example isNumeric("-45.6") => true
+ * @example isNumeric("abc") => false
+ * @example isNumeric("12.3.4") => false
+ */
+const isNumeric = (str) => {
+  if (typeof str !== 'string') {
+    throw new TypeError('Input must be a string')
+  }
+  if (str.trim() === '') return false
+  return !isNaN(str) && !isNaN(parseFloat(str))
+}
+
+export { isNumeric }

String/test/IsNumeric.test.js

@@ -0,0 +1,51 @@
+import { isNumeric } from '../IsNumeric.js'
+
+describe('isNumeric', () => {
+  test("isNumeric('123') returns true", () => {
+    expect(isNumeric('123')).toBe(true)
+  })
+
+  test("isNumeric('-45.6') returns true", () => {
+    expect(isNumeric('-45.6')).toBe(true)
+  })
+
+  test("isNumeric('0') returns true", () => {
+    expect(isNumeric('0')).toBe(true)
+  })
+
+  test("isNumeric('3.14') returns true", () => {
+    expect(isNumeric('3.14')).toBe(true)
+  })
+
+  test("isNumeric('abc') returns false", () => {
+    expect(isNumeric('abc')).toBe(false)
+  })
+
+  test("isNumeric('12.3.4') returns false", () => {
+    expect(isNumeric('12.3.4')).toBe(false)
+  })
+
+  test("isNumeric('') returns false", () => {
+    expect(isNumeric('')).toBe(false)
+  })
+
+  test("isNumeric('  ') returns false", () => {
+    expect(isNumeric('  ')).toBe(false)
+  })
+
+  test("isNumeric('123abc') returns false", () => {
+    expect(isNumeric('123abc')).toBe(false)
+  })
+
+  test("isNumeric('-0') returns true", () => {
+    expect(isNumeric('-0')).toBe(true)
+  })
+
+  test('throws TypeError for non-string input', () => {
+    expect(() => isNumeric(123)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for null input', () => {
+    expect(() => isNumeric(null)).toThrow(TypeError)
+  })
+})