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
It conflicts with an inbuilt TypeScript `Request` type so can cause
confusion when in TS land. Note: `Response.ts` and `Worker.ts` also
suffer from this; PRs to rename them are incoming.
We should import them just like any other module. This commit makes that
change. It does not change any behaviours or the types themselves.
EXPECTED_PROTOCOL_DIFF as we're updating the structure of it.
* chore: Remove src/TaskQueue
The only place it's used is in `src/Page.ts` to have a chain of
screenshot promises. Rather than initialize a task queue in `Browser`
and pass it through a chain of constructors we instead move the class
into `src/Page` and define it inline.
In the future we might want to create a helpers folder to contain small
utilities like that (`src/Page.ts` is already far too large) but I'm
leaving that for a future PR.
`TaskQueue` isn't documented in `api.md` so I don't think this is a
breaking change.
I updated the type of `screenshot()` to return `Promise<string | Buffer
| void>` because if a promise rejects it's silently swallowed. I'd like
to change this behaviour but one step at a time. This type only had to
change as now we type the screenshot task queue correctly rather than
using `any` which then exposed the incorrect `screenshot()` types.
* chore: remove src/externs.d.ts
It defined global types that we don't want to use, and instead we move
to using interfaces that we import and reference just like with any
other interface.
This means other than Protocol (which I think is fine to leave as is),
there are no other magic global types and you have to import any types
or interfaces that you want.
* chore: migrate src/Page.js to TypeScript
The final one! This is a huge file and needs to be split up and tidied,
but for now I've left all the definitions in place and converted types
accordingly.
There's some additional tidying we can do now every `src` file is TS,
but I'll leave that for another PR to avoid this one getting any bigger.
Co-authored-by: Mathias Bynens <mathias@qiwi.be>
