Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops Refactor Using a Loop

Posted by Joy Faber
Joy Faber
3,843 Points

There was an error with your code: ReferenceError: Strict mode forbids implicit creation of global property 'j'

ik keep getting this error and dont know what it means. while my code is 100% correct.

script.js 
for ( j = 2 ; j <= 24; j +=2)
{
console.log(j);
}
index.html 
<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JavaScript Loops</title>
</head>
<body>
<script src="script.js"></script>
</body>
</html>
Usman Badar
Usman Badar
9,304 Points

Please declare data type of j in the start of the for loop such as var.

1 Answer

Zimri Leijen
Zimri Leijen
11,835 Points
Zimri Leijen
Zimri Leijen
11,835 Points 
for (let j = 2 ; j <= 24; j +=2)
{
console.log(j);
}

since you're not explicitly declaring j (using let or var) it's throwing errors.

Joy Faber
Joy Faber
3,843 Points

ah... got it thanks