Javascript: add hint to Return Early Pattern for Functions (#19118)

Add hint to Return Early Pattern for Functions (https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-javascript/return-early-pattern-for-functions/ and https://guide.freecodecamp.org/certifications/javascript-algorithms-and-data-structures/basic-javascript/return-early-pattern-for-functions/)

client/src/pages/guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/return-early-pattern-for-functions/index.md

@@ -1,10 +1,54 @@
----
+
-title: Return Early Pattern for Functions
----
 ## Return Early Pattern for Functions
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/javascript-algorithms-and-data-structures/basic-javascript/return-early-pattern-for-functions/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
-
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
-
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+
+Here’s a setup:
+
+```javascript
+// Setup
+function abTest(a, b) {
+  // Only change code below this line
+  
+  // Only change code above this line
+  return Math.round(Math.pow(Math.sqrt(a) + Math.sqrt(b), 2));
+}
+// Change values below to test your code
+abTest(2,2);
+```
+
+We need to modify the function ```abTest``` so that if ```a``` or ```b``` are less than ```0``` the function will immediately exit with a value of ```undefined```.
+
+We add in body of function simple ```if``` statement, which, under the conditions "if ```a``` or ```b``` are less than ```0``` - immediately exit with a value of ```undefined```":
+
+```javascript
+  if (a < 0 || b < 0) {
+    return undefined;
+  }
+```
+
+Now, if ```a``` or ```b``` are less than ```0``` - function exit with a value of ```undefined```, in other cases - 
+
+```javascript
+ return Math.round(Math.pow(Math.sqrt(a) + Math.sqrt(b), 2));
+  }
+```
+
+  Here’s a full solution:
+  
+   ```javascript
+   // Setup
+function abTest(a, b) {
+  // Only change code below this line
+  if (a < 0 || b < 0) {
+    return undefined;
+  }
+ 
+  // Only change code above this line
+
+  return Math.round(Math.pow(Math.sqrt(a) + Math.sqrt(b), 2));
+}
+
+// Change values below to test your code
+abTest(2,2);
+   ```