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Asked: 2024-12-19T07:57:06+05:30

I’m encountering issues while trying to use JavaScript’s URL library within a BigQuery User-Defined Function (UDF). Could anyone provide guidance on why this might not be functioning as expected? What are the limitations or compatibility concerns I should be aware of when working with JavaScript in this context?

I’m having a bit of a rough time using JavaScript’s URL library inside a BigQuery User-Defined Function (UDF) and could really use some help here. So, I tried to write a UDF that processes URLs, but I keep running into issues that I can’t seem to figure out.

Basically, what I want to achieve is to extract certain components of a URL, like the hostname or the path, using the URL library that’s native to JavaScript. However, when I run my query, it feels like it’s just not recognizing the library at all. I mean, I made sure to reference it properly, but I keep getting errors that are driving me nuts! I’m wondering if there are certain limitations with the JavaScript environment in BigQuery that I’m not aware of.

I’ve read a bit about how BigQuery implements JavaScript UDFs, but honestly, it’s a bit cloudy. Are there any specific functions or features of modern JavaScript that aren’t supported in BigQuery’s UDFs? Like, can I use the URL constructor or is it simply a no-go? Plus, are there any quirks or compatibility concerns with the version of JavaScript that BigQuery uses?

Also, I’m curious if anyone has come across any workarounds or alternative methods to parse URLs without using the URL library. Are there maybe some regex tricks that work just as well? I’m all ears for any hacks or tips you might have!

It feels like I’m missing something fundamental here, and I’d love some clarity. If anyone could shed some light on what I’m doing wrong or share their experiences with JavaScript in BigQuery, it would help me tremendously. I’d hate to spend more time pulling my hair out over this! Thanks a bunch!

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    2 Answers

    1. Sounds like you’re having a tough time with that! It can be super frustrating when things don’t work like you expect them to, especially when you’re trying to use the URL library in a BigQuery JavaScript UDF.

      So, here’s the thing: BigQuery only supports a subset of the JavaScript language. When it comes to the URL library, it’s not fully available, and that’s probably why you’re running into issues. Some libraries and features you’d find in a modern JavaScript environment aren’t implemented in BigQuery’s version. The JavaScript environment in BigQuery is limited, which means features like the URL constructor might just not be there.

      If you want to extract components of a URL, you might want to try using regular expressions. Regex can be pretty handy for parsing URLs without needing the URL library. For example, if you want to get the hostname or path, you could write regex patterns that match those specific parts. It might take a little time to get the regex right, but it could be more reliable within the constraints of BigQuery.

      Here’s a simple example for getting the hostname using regex:

              const regex = /^(?:https?:\/\/)?(?:www\.)?([^\/]+)/;
        const url = "https://www.example.com/path/to/resource";
        const match = url.match(regex);
        return match ? match[1] : null;

      It’s also worth checking out the BigQuery documentation on JavaScript UDFs to understand what functions are supported and what limitations there might be. They might have updates or examples that could help you out, too!

      Don’t get discouraged; just keep experimenting, and you’ll get the hang of it! Good luck!

    2. Using JavaScript’s URL library within BigQuery User-Defined Functions (UDFs) can indeed be challenging due to certain limitations in the JavaScript environment that BigQuery provides. The version of JavaScript supported in BigQuery is based on the V8 engine, and while it includes many modern features, it does not support all of the standard libraries and APIs you’d normally expect in a browser or Node.js environment. Specifically, the URL API you’re trying to use may not be available, which is likely the source of the errors you’re encountering. It would be beneficial to review the documentation on BigQuery’s JavaScript UDFs to identify supported features and understand better the limitations of the execution context. Generally, many complex objects and methods are more restrictive in these environments.

      If the URL library cannot be used, regex is often a viable alternative for parsing URLs. For instance, you can create regex patterns to extract specific components like the hostname or the path. Here’s a simplified example: to extract the hostname, you could use a regex such as `/^(?:https?:\/\/)?(?:www\.)?([^\/]+)/i` which would capture the hostname. This approach is effective for basic URL parsing, although you should be careful with the edge cases. You might also consider using string manipulation functions in JavaScript (like `split()`, `indexOf()`, etc.) as alternative methods to dissect the URL into its components without relying on the URL object. Gathering feedback from others who have faced similar issues can provide more insights into workable strategies within the constraints of BigQuery.