Improve the JS performance for logic-heavy stylesheets #760
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srawlins
approved these changes
Jul 14, 2019
| var positionalNodes = trackSpans | ||
| ? [ | ||
| for (var expression in arguments.positional) | ||
| _expressionNode(expression) |
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Good that this new syntax is performant!
| @@ -40,7 +40,7 @@ void _js({@required bool release}) { | |||
| // * We expect our test coverage to ensure that nothing throws subtypes of | |||
| // Error. | |||
| // * We thoroughly test edge cases in user input. | |||
| if (release) ...["-O4", "--fast-startup"] | |||
| if (release) ...["-O4", "--no-minify", "--fast-startup"] | |||
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Should we comment on why we pass no-minify?
The JS size doesn't really matter on the server side, and this makes profiling the release-mode binary substantially easier, as well as improving the quality of stack traces provided by downstream users.
The default implementation runs a type check, which was a performance bottleneck when compiled to JS. There's no need for this type check in practice, since we never pass a non-String value to the contains(), containsKey(), or remove() methods (and if we do, it will throw a TypeError in our tests).
As well as being arguably more readable, the toList() method was running a type check that was showing up as a minor bottleneck in JS profiles.
As expected, this substantially improves the JS performance in logic-heavy benchmarks. I believe the other changes are just noise.
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See #113