Can You Load JavaScript Synchronously with document.createElement(\"script\")?

Synchronous Loading of JavaScript with document.createElement("script")

In web development, it is often necessary to load external JavaScript files asynchronously to avoid blocking the page from rendering. However, there may be situations where you want to load a script synchronously and use it immediately afterwards.

The question at hand explores the possibility of synchronously loading a JavaScript file (my.js) and immediately using the functions defined within. The provided code snippet attempts to achieve this by creating a script element dynamically using document.createElement("script") and appending it to the head element.

Unfortunately, as the answer correctly points out, it is not possible to load JavaScript synchronously in this manner. When a script is loaded dynamically, the browser executes it asynchronously. This means that while the script will be loaded eventually, there is no guarantee when this will happen. Consequently, attempting to call functions from the loaded script immediately after its creation may fail.

The answer suggests using the onload event handler on the script element to execute code when the script has finished loading. While this can work in some cases, it is not fully reliable and may not always fire. Especially if the loaded script injects another script that contains the desired function.

To improve the reliability of synchronous script loading, you can consider using a different approach. The answer mentions two options:

1. XHR and Eval: Fetch the script using an XMLHttpRequest (XHR) and then dynamically evaluate (eval()) its content. This ensures that the script is executed immediately, providing a synchronous-like behavior. However, it's important to note that evaluating code in this way can have security implications and should be used with caution.
2. Custom Script Loading Tool: Use a robust script loading tool like RequireJS or YepNope. These tools provide a more controlled and reliable way to load and manage JavaScript dependencies. They handle complex scenarios and account for edge cases, making it easier to use external scripts synchronously or asynchronously.

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