Why Does It Print undefined on the Console in JavaScript?

Discover why your JavaScript console outputs `undefined` when calling functions, and learn how to fix it for cleaner code outputs!
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Understanding undefined Outputs in JavaScript Functions

If you're venturing into JavaScript, you've probably encountered strange behavior when it comes to function returns, especially when console logging the results. One common source of confusion is when you see undefined printed in the console after your function calls. This guide aims to dissect this issue, specifically addressing the question:

Why does it print "undefined" on the console?

The Problem

Consider the following JavaScript code snippet:

[[See Video to Reveal this Text or Code Snippet]]

When you run this code, the output seems puzzling:

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You might have expected an output that looks like this:

[[See Video to Reveal this Text or Code Snippet]]

So, why the undefined?

The Explanation

Functions in JavaScript

In JavaScript, when a function does not explicitly return a value, it returns undefined by default. This is crucial to understand when working with console logging. Here's how it plays out in your code:

Calling the Functions:

Logging the Output:

Why the undefined Matters

Code Clarity: Having undefined printed cluttering your console can make it difficult to read your logs, especially in larger applications.

Return Statements: Functions are usually expected to return values, and using return statements can help maintain clarity.

How to Fix It

To avoid the undefined output and make your code cleaner, simply return the necessary value from your functions. Here’s how you can modify your code:

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Expected Output After Fix

Now, when you run the modified code, the output should be exactly what you expected without any undefineds appearing:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Understanding why undefined appears in your JavaScript console when calling functions is key to writing cleaner and more maintainable code. By ensuring your functions return values when necessary, you can enhance readability and make debugging much easier. Armed with this knowledge, you can tackle similar issues with confidence in your coding endeavors. Happy coding!