feat(isNumeric): add isNumeric function (#112)

* feat(isNumeric): add isNumeric function

* fixing indentation

Author: Ibrahim Sassi

src/index.js

@@ -37,6 +37,7 @@ import round from './round'
 import checkPalindrome from './checkPalindrome'
 import isFunction from './is-function'
 import isOdd from './is-odd'
+import isNumeric from './is-numeric'
 
 export {
   isOdd,
@@ -78,5 +79,6 @@ export {
   checkPalindrome,
   isFunction,
   subtraction,
+  isNumeric,
 }
 

src/is-numeric.js

@@ -0,0 +1,15 @@
+export default isNumeric
+
+/**
+ * Original Source:
+ * https://stackoverflow.com/questions/9716468/is-there-any-function-like-isnumeric-in-javascript-to-validate-numbers
+ *
+ * This method will check whether an expression can be evaluated as a number or not.
+ *
+ * @param {Object} n - number to check
+ * @return {Boolean} - True if n is numeric, false if not
+ */
+function isNumeric(n) {
+  return !isNaN(parseFloat(n)) && isFinite(n)
+}
+

test/is-numeric.test.js

@@ -0,0 +1,19 @@
+/**
+ * Created by Ibrahim on 07/08/2017.
+ */
+import test from 'ava'
+import {isNumeric} from '../src'
+
+test('checks if expression is number and returns true', t => {
+    const n = "5";
+    const expected = true;
+    const actual = isNumeric(n);
+    t.deepEqual(actual, expected)
+});
+
+test('checks if expression is number and returns false', t => {
+    const n = "hello";
+    const expected = false;
+    const actual = isNumeric(n);
+    t.deepEqual(actual, expected)
+});