feat(@angular/ssr): add modulepreload for lazy-loaded routes
#28919
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Thanks for putting this together! I left some initial thoughts.
I think my biggest concern is that I'm not sure how comfortable I am .toString()-ing a function and parsing out the dynamic import() statement at runtime in a production server. It's hard to explain concrete concerns, but it feels off to have a program inspect its own source code and alter behavior as a result.
I'm curious to explore if there is an opportunity with a compiler transform to create a similar result without having to toString an arbitrary function? Let's chat about this and see what our options are. @AndrewKushnir might also be interested in this.
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Consider: Users can do pretty weird things in the HTML like:
<!DOCTYPE html>
<html>
<body>
<!-- ... -->
</body>
<script>
document.documentElement.outerHTML.replace('</body>', '</body><script src="..."></script>');
</script>
</html>Technically the last </body> would be in the JS, not the HTML.
It's a pretty extreme scenario, so I don't know that we really need to be too concerned about it. The "correct" solution is likely using a real HTML parser, but that might be worth it for this kind of edge case.
I mainly just wanted to point out this potential issue, up to you if it's worth solving. If we do choose to leave this, I would recommend at least having a comment which calls out that behavior.
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This is quite an extreme edge case, that I feel that we should not worry about right now.
tests/legacy-cli/e2e/tests/build/server-rendering/server-routes-preload-links.ts
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This only happens during the build, when building the manifest, on a production server the preloads are already extracted. |
Enhance performance when using SSR by adding `modulepreload` links to lazy-loaded routes. This ensures that the required modules are preloaded in the background, improving the user experience and reducing the time to interactive. Closes angular#26484
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Enhance performance when using SSR by adding
modulepreloadlinks to lazy-loaded routes. This ensures that the required modules are preloaded in the background, improving the user experience and reducing the time to interactive.Closes #26484