Fix the code sample from dart web get started guide

[jsiedentop]

I have discovered that the dart web get started code example does not match the new dart:web interface. Therefore I have updated the documentation.

Fixes: There is no specific issue, but it certainly helps #5674 and #5525

---

• I’ve reviewed the contributor guide and applied the relevant portions to this PR.
• This PR doesn't contain automatically generated corrections or text (Grammarly, LLMs, and similar).
• This PR follows the Google Developer Documentation Style Guidelines — for example, it doesn't use i.e. or e.g., and it avoids I and we (first person).
• This PR uses semantic line breaks of 80 characters or fewer.

Contribution guidelines:

• See our contributor guide for general expectations for PRs.
• Larger or significant changes should be discussed in an issue before creating a PR.
• Code changes should generally follow the Dart style guide and use dart format.
• Updates to code excerpts indicated by <?code-excerpt need to be updated in their source .dart file as well.

[MaryaBelanger]

Hi @jsiedentop! This is so helpful, thank you.
I'll take a look at the test failures and let you know how we can fix it, stay tuned!

[parlough]

Thanks for thinking about this and for the PR!

The build is failing as the [! highlight mechanism currently doesn't support multi-line spans. The goal is to transition away from this mechanism in the future, so support likely won't be added. To work around this limitation, you can add the brackets to each line :)

[jsiedentop]

I haven't had a chance to set up the development environment locally to see why the build is failing. Thanks for taking a quick look.

It's a bit offtopic but I have some feedback on the documentation: If someone wants to get started with Vanilla Dart on the web, the DevEx is currently suboptimal. My impression of the last few days, was that it takes good will and a lot of extra effort to get into web development with Dart. However, I've noticed that there is a lot going on at the moment (new web/js_interop libraries, wasm, extension types, more documentation).

Would you be interested in me writing down my experiences in more detail in a suitable place? But if the topic doesn't fit into the agenda currently, I wouldn't create an issue. Unlike good wine, issues don't really get better with time 😉

[parlough]

It's a bit offtopic but I have some feedback on the documentation: If someone wants to get started with Vanilla Dart on the web, the DevEx is currently suboptimal. [...] However, I've noticed that there is a lot going on at the moment.

You're right that the experience is evolving a lot recently and there's still a lot of work in progress, particularly for documentation. Beyond that, as you noticed, there are some developer experience tradeoffs with the new interop mechanisms. It's my understanding that some of these are unavoidable due to other goals (such as Wasm compatibility and performance), but it seems the team working on it is very interested in improving the developer experience where they can. So send feedback their way :)

Would you be interested in me writing down my experiences in more detail in a suitable place?

Feedback is always appreciated, and is even more impactful while Dart's web story is continuing to evolve :D

If you don't have anything super specific or just want one place to file your thoughts, https://github.com/dart-lang/sdk/issues is likely a good place to at least have your feedback be heard.

However, if you have feedback related to specific portions, it can help to separate that discussion into more focused issues. The following table has some related topics and where feedback for them might be the most helpful.

Topic	Relevant repository
JS interop	dart-lang/sdk
package:web	dart-lang/web
Extension types from a language or syntax perspective	dart-lang/language
Extension types in relation to JS interop	dart-lang/sdk
The webdev tool	dart-lang/webdev
Tooling/IDE DevEx for JS/web development	dart-lang/sdk
Web/JS interop documentation	dart-lang/site-www

[parlough]

/gcbrun

[parlough]

Thanks for catching this and the PR! Looks good to me :)

I pushed some more formatting fixes to fix the build and some other nearby cleanup.

[dart-github-bot]

Visit the preview URL for this PR (updated for commit 2c2d86d):

https://dart-dev--pr5688-update-dart-web-example-3utizk7u.web.app