JavaScript function not recognized when called from separate file

Other Questions JavaScript
1

I’m working on a project where I have many functions that need to bind to various DOM elements. To keep things organized, I put all my functions in a separate JavaScript file and try to call them from my main script file.

My HTML structure:

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>My Application</title>
    <script src="~/scripts/jquery.min.js"></script>
    <script src="~/scripts/utilities.js"></script>
    <script src="~/scripts/main.js"></script>
</head>
<body>
    <div>
        Welcome to my application!
    </div>
</body>
</html>

utilities.js file:

$(document).ready(function () {
    // I have around 50+ similar functions here
    function FetchUserData() {
        // performs ajax request
        console.log('Fetching user information...');
    }
});

main.js file:

$(document).ready(function () {
    FetchUserData();
});

When I run this code, I get the following error message:

Uncaught ReferenceError: FetchUserData is not defined

What’s causing this issue and how can I properly call functions from one JavaScript file in another?

2

Your function’s stuck inside the $(document).ready callback in utilities.js, so main.js can’t see it. I’ve run into this before - just move the function outside that block and it’ll be globally accessible. Then you can call FetchUserData from main.js without any reference errors. Or if you want to keep things cleaner, create a namespace like var MyApp = { FetchUserData: function() {…} } to avoid cluttering the global scope.

3

yup, ur function is hidden inside the $(document).ready. just move FetchUserData outta that scope in utilities.js or use window.FetchUserData = function(){…} to make it globally available. then it should work in main.js!

4

This happens because of JavaScript’s function scope rules. When you declare a function inside $(document).ready(), it’s only available within that callback function. I ran into this exact same issue last year while refactoring a big app. Easiest fix? Define your functions outside the ready block in utilities.js, then call them inside ready blocks when you need them. You could also attach functions to the window object or use a proper module pattern. I prefer declaring functions globally in utilities.js and calling them from ready callbacks - keeps initialization separate from function definitions and makes debugging way easier.