Why is my global variable not accessible across multiple JavaScript files?

Global Variables in JavaScript Across Multiple Files

In many JavaScript applications, code is organized into separate files to improve modularity and maintainability. However, when working with global variables across these files, certain limitations can arise.

The Issue:

A developer wrote a JavaScript file named "helpers.js" and included it in an HTML document. Within the HTML code, they wanted to check if a specific function from "helpers.js" had been called. To achieve this, they defined a global variable ("myFunctionTag") in both the HTML code and "helpers.js." However, when they tried to access "myFunctionTag" in the HTML code, it always returned "false," even though it was set to "true" in "helpers.js."

The Solution:

In JavaScript, global variables are declared at the top-level scope. When a variable is declared inside a script tag, it creates a new scope and does not affect variables declared in other script tags.

To ensure that the global variable ("myFunctionTag") is accessible in both the HTML code and "helpers.js," it should be declared outside of any script tags. Here's the corrected HTML code:

<code class="html"><script type="text/javascript">
  var myFunctionTag = false;  <!-- Declare the global variable outside of any script tag -->
</script>
<script type="text/javascript" src="js/helpers.js"></script>    </code>

By declaring the global variable outside of script tags, it is now available to all subsequent code, including the "helpers.js" file. This allows the developer to check the status of "myFunctionTag" from the HTML code and take appropriate actions based on whether the function has been called.

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