Console.log() and Undefined?

jakey · Jan 14, 2026

I have been trying to learn JavaScript and everything has been alright so far. Then i tried to output a value for a variable i had created
using console.log() and at each and every attempt the output has been the same "undefined". The tutorials I have come across shows the following:

Code:

                     console.log("Hello, World!");
                     Output: undefined

is there anyway i can get around this in Firefox?

Saul H. · Jan 14, 2026

Did you nest the console.log() function in a script tag (this only applies if your code was a .html file)? If it was written in Javascript (.js), this does not apply. I will provide two examples of how to log a message to the console, one in a .js file and one in a .html file.

HTML:

<!DOCTYPE html>
<html>
    <head>
        <title>HTML Console</title>
    </head>
<body>
    <p>How to log to the console in a .html file.</p>
    <script>
        console.log("Hello World");
    </script>
    </body>
</html>

JavaScript:

console.log("Hello World");

Hopefully you can see the distinction between the two filetypes and what is needed to log something to the console in these respective filetypes.

jakey · Jan 15, 2026

Hi Saul H
I can see and understand where you are coming from with the first example but would like to see
the second .js example if you don't mind. Thanks

Saul H. · Jan 15, 2026

I provided the example. It's purely the function, not nested inside of any sort of script tag because there is no need to specify that the language is Javascript.

VBService · Jan 30, 2026

jakey said:
is there anyway i can get around this in Firefox?

In Firefox, the console shows both what console.log() prints and the value returned by the expression.
The function console.log() always returns undefined.
Because of this, Firefox displays undefined after the logged message.
This is normal behavior and not a JavaScript error.
Other browsers, like Chrome, usually hide the return value, which is why tutorials look different.
You can safely ignore undefined or type the variable name directly in the console to see its value.

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Console.log() and Undefined?

jakey

Saul H.

jakey

Saul H.

VBService

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