Replacing the Node EventEmitter with Mitt caused more problems than
anticipated for end users due to the API differences and the amount of
people who relied on the EventEmitter API. In hindsight this clearly
should have been explored more and then released as a breaking v4.
This commit rolls us back to the built in Node EventEmitter library
which we can release to get everyone back on stable builds. We can then
consider our approach to migrating to Mitt and when we do do that we can
release it as a breaking change and properly document the migration
strategy and approach.
* chore: migrate to Mitt as the EventEmitter
This commit moves us to using Mitt [1] for the event emitter in
Puppeteer. This removes our dependency to Node's EventEmitter which is
part of a larger stream of work to enable a Puppeteer-web version that
doesn't depend on Node.
There are no large breaking changes as we support the main methods that
EventEmitter had, but it also provides some methods that Puppeteer
didn't use. Technically end users could depend on this but it's
unlikely.
[1]: https://github.com/developit/mitt
closes#5719
Original stream.pipeline issue has been fixed in Node 14.1.0 and above.
Meanwhile, the workaround itself caused timout failures in many CI Node 14 runs, as reported in #5719.
Removed it, as it's no longer needed, and actually blocks consumers from adding CI testing on Node 14.
* chore: Useful error for Node v14 breakage
There is currently a bug with extract-zip and Node v14.0.0 that
causes extractZip to silently fail:
https://github.com/puppeteer/puppeteer/issues/5719
Rather than silenty fail if the user is on Node 14 we instead
detect that and throw an error directing the user to that bug. The
rejection message below is surfaced to the user in the command line.
The issue seems to be in streams never resolving so we wrap the call in
a timeout and give it 100ms to resolve before deciding on an error. If
the user is on Node < 14 we maintain the behaviour we had before this
patch.
Here's how this change impacts the output on Node 14 and Node 10:
Node 10:
```
npm run tsc && rm -r .local-* && node install
> puppeteer@3.0.1-post tsc /Users/jacktfranklin/src/puppeteer
> tsc --version && tsc -p . && cp src/protocol.d.ts lib/ && cp src/externs.d.ts lib/
Version 3.8.3
Downloading Chromium r737027 - 118.4 Mb [====================] 100% 0.0s
Chromium (737027) downloaded to /Users/jacktfranklin/src/puppeteer/.local-chromium/mac-737027
```
---
Node 14 without this patch:
```
npm run tsc && rm -r .local-* && node install
> puppeteer@3.0.1-post tsc /Users/jacktfranklin/src/puppeteer
> tsc --version && tsc -p . && cp src/protocol.d.ts lib/ && cp src/externs.d.ts lib/
Version 3.8.3
Downloading Chromium r737027 - 118.4 Mb [====================] 100% 0.0s
```
Note that whilst it doesn't error, it doesn't complete the install. We
don't get the success message that we saw above in the Node 10 install.
---
Node 14 with this patch:
```npm run tsc && rm -r .local-* && node install
> puppeteer@3.0.1-post tsc /Users/jacktfranklin/src/puppeteer
> tsc --version && tsc -p . && cp src/protocol.d.ts lib/ && cp src/externs.d.ts lib/
Version 3.8.3
Downloading Chromium r737027 - 118.4 Mb [====================] 100% 0.0s
ERROR: Failed to set up Chromium r737027! Set "PUPPETEER_SKIP_DOWNLOAD" env variable to skip download.
Puppeteer currently does not work on Node v14 due to an upstream bug. Please see https://github.com/puppeteer/puppeteer/issues/5719 for details.
```
The explicit message should save users a good amount of debugging time.
