Why JavaScript Code Fails on jsfiddle.net

The provided code exhibits an issue when attempting to run on jsfiddle.net, with the console logging "ReferenceError: Function Name is not defined." To understand this, we delve into the structure of the code and analyze its execution within jsfiddle.

The code defines functions such as BetterSelect and fillList within a function called window.onload. In a typical web environment, this function ensures that the code executes once the window has loaded. However, within jsfiddle's framework, this aspect introduces a crucial distinction.

When the code is executed on a live site, the functions are available globally within the window object because they are defined outside of any specific function scope. However, in jsfiddle, the functions are only accessible within the window.onload function's scope.

There are several solutions to this issue:

1. Globally Define Functions: Change function declarations to window.functionName = function(){};.
2. Unobtrusive JavaScript: Separate HTML from JS to attach behavior to DOM elements through JS only.
3. Disable jsfiddle's Default Wrapping: Select "No Wrap" (body or head) instead of "onLoad."

By addressing this scoping issue, you can ensure that your JavaScript code executes correctly on both live sites and jsfiddle.net.