misc: avoid splitting node labels in the middle of unicode surrogate pairs

[wildlyinaccurate]

Summary

Potential fix for #11697. Takes advantage of the fact that the ES6 string iterator is unicode-aware.

Related Issues/PRs

fix for part of #11697

[patrickhulce]

thanks very much @wildlyinaccurate! 🎉

great find, PR much appreciated :)

[wildlyinaccurate]

Thanks for the suggestions @patrickhulce - much appreciated!

[wildlyinaccurate]

yarn update:test-devtools is failing on my machine. I'm not sure if I need to manually update some of the expected output fixtures or not?

[patrickhulce]

It's actually failing on master too @wildlyinaccurate , so not your doing. We'll let this chill for a bit until we're back up and running 👍

[connorjclark]

master on my machine:

[patrickhulce]

@connorjclark it's in CI too https://github.com/GoogleChrome/lighthouse/runs/1434349934#step:15:206

[connorjclark]

Just landed #11702 to fix master.

How is yarn update:test-devtools failing, can you share the output? FYI it only works on Mac at the moment.

[patrickhulce]

FWIW I don't think you'll need to run yarn update:test-devtools once this is rebased though

[connorjclark]

I think the other 2 usages of .slice here are susceptible to the same issue. Hard to analyze the entire codebase tho, would be nice if one could search for [String].slice using the typescript parser.

[patrickhulce]

I think the other 2 usages of .slice here are susceptible to the same issue. Hard to analyze the entire codebase tho, would be nice if one could search for [String].slice using the typescript parser.

There are many usages of .slice across LH that are susceptible to this issue. How do you feel about just leaving open #11697 for investigation by the team but still landing this PR?

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[patrickhulce]

@paulirish how do you feel about this skipping this check entirely if it's from a fork for now instead and we can sort out the fix later?

[paulirish]

that works for me.. though determining that would probably have required almost this much iteration as well... so i think it's all moot.

ALL MOOT!

[wildlyinaccurate]

Hey, uh, does it help if I resubmit this against master as a single commit?

[paulirish]

Hey, uh, does it help if I resubmit this against master as a single commit?

haha nah man it's all good. we'll just all pretend I never had to make all that noise. the bug i had is fixed (as of my last commit), but it ends up not mattering.

This should be good to go once the yarn install flake timeout is gone.

[paulirish]

@wildlyinaccurate btw this is a fantastic find and fix. Nice work. :D