Implement _check

src/calculator.js

@@ -1,47 +1,33 @@
-exports._check = () => {
+exports._check = (x,y) => {
   // DRY up the codebase with this function
   // First, move the duplicate error checking code here
   // Then, invoke this function inside each of the others
   // HINT: you can invoke this function with exports._check()
-};
-
-exports.add = (x, y) => {
   if (typeof x !== 'number') {
     throw new TypeError(`${x} is not a number`);
   }
   if (typeof y !== 'number') {
     throw new TypeError(`${y} is not a number`);
   }
+};
+
+exports.add = (x, y) => {
+  exports._check(x,y);
   return x + y;
 };
 
 exports.subtract = (x, y) => {
-  if (typeof x !== 'number') {
-    throw new TypeError(`${x} is not a number`);
-  }
-  if (typeof y !== 'number') {
-    throw new TypeError(`${y} is not a number`);
-  }
+  exports._check(x,y);
   return x - y;
 };
 
 exports.multiply = (x, y) => {
-  if (typeof x !== 'number') {
-    throw new TypeError(`${x} is not a number`);
-  }
-  if (typeof y !== 'number') {
-    throw new TypeError(`${y} is not a number`);
-  }
+  exports._check(x,y);
   return x * y;
 };
 
 exports.divide = (x, y) => {
-  if (typeof x !== 'number') {
-    throw new TypeError(`${x} is not a number`);
-  }
-  if (typeof y !== 'number') {
-    throw new TypeError(`${y} is not a number`);
-  }
+  exports._check(x,y);
   return x / y;
 };