Fixing Uncaught SyntaxError: Unexpected identifier Error in Bookmarklets

Описание: Learn how to resolve the common `Uncaught SyntaxError: Unexpected identifier` error in your JavaScript bookmarklet by understanding the common pitfalls and proper function definition practices.
---
This video is based on the question https://stackoverflow.com/q/68248520/ asked by the user 'Joseph U.' ( https://stackoverflow.com/u/411409/ ) and on the answer https://stackoverflow.com/a/68249435/ provided by the user 'vsemozhebuty' ( https://stackoverflow.com/u/2625560/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Uncaught SyntaxError: Unexpected identifier within bookmarklet

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting Uncaught SyntaxError: Unexpected Identifier in Bookmarklets

If you've ever tried to write a JavaScript bookmarklet, you may have come across the frustrating error Uncaught SyntaxError: Unexpected identifier. This error can stop your code in its tracks, making it impossible to execute your desired actions. In this guide, we'll explore the common causes of this error and how to resolve it effectively.

Understanding the Problem

The issue often arises when injecting external scripts into web pages, particularly when using callback functions. In the case of the error we’re addressing, it stems from a missing semicolon, which can lead to ambiguous interpretations of code by the JavaScript engine.

Example of the Problematic Code

Consider the following code snippet that throws the Unexpected identifier error:

[[See Video to Reveal this Text or Code Snippet]]

The code above appears to be all in order, but it’s crucial to take a closer look at the formatting in the context of a bookmarklet.

Analyzing the Error

The Uncaught SyntaxError: Unexpected identifier occurs due to the way function definitions and calls are structured in a single line of code. Here's what happens:

Missing Semicolon: When you remove the whitespace from your bookmarklet, the absence of a semicolon between the function definition and the function call creates an illegal JavaScript sequence. This leads to confusion in parsing the code structure.

Example of the Problematic Sequence:

[[See Video to Reveal this Text or Code Snippet]]

This fundamentally incorrect structure makes it impossible for JavaScript to understand where one statement ends and the next begins.

The Solution

Revised Working Code

Here’s how to properly define your function and call it without triggering the syntax error:

[[See Video to Reveal this Text or Code Snippet]]

Key Changes Made

Semicolon Usage: Ensure that there is a semicolon ; after every statement to clearly indicate the end of that statement.

Function Definition: Moved the inline function to a standard function declaration format, making it easier to read and work with.

Use document.head: Updated document.body to document.head for improved script loading behavior.

Conclusion

By understanding the syntax rules of JavaScript and how they apply to bookmarklets, you can avoid the Uncaught SyntaxError: Unexpected identifier. Remember to include semicolons where needed, and keep your code well-structured for clarity. With these adjustments, you can successfully inject libraries like jQuery into your web pages without hassle.

If you have any questions or further issues, feel free to reach out in the comments below! Happy coding!