By adding support for an environment variable `PUPPETEER_DOWNLOAD_PATH` it is possible to support downloading the browser binaries into a folder outside the `node_modules` folder. This makes it possible to preserve previously downloaded binaries in order to skip downloading them again.
* chore: Use devtools-protocol package
Rather than maintain our own protocol we can instead use the devtools-protocol package and pin it to the version of Chromium that Puppeteer is shipping with.
The only changes are naming changes between the bespoke protocol that Puppeteer created and the devtools-protocol one.
This change started as a small change to pull types from DefinitelyTyped over to
Puppeteer for the `evaluateHandle` function but instead ended up also fixing
what looks to be a long standing issue with our existing documentation.
`evaluateHandle` can in fact return an `ElementHandle` rather than a `JSHandle`.
Note that `ElementHandle` extends `JSHandle` so whilst the docs are technically
correct (all ElementHandles are JSHandles) it's confusing because JSHandles
don't have methods like `click` on them, but ElementHandles do.
if you return something that is an HTML element:
```
const button = page.evaluateHandle(() => document.querySelector('button'));
// this is an ElementHandle, not a JSHandle
```
Therefore I've updated the original docs and added a large explanation to the
TSDoc for `page.evaluateHandle`.
In TypeScript land we'll assume the function will return a `JSHandle` but you
can tell TS otherwise via the generic argument, which can only be `JSHandle`
(the default) or `ElementHandle`:
```
const button = page.evaluateHandle<ElementHandle>(() => document.querySelector('button'));
```
As far as I can tell these became irrelevant as of v1.15 which added
`puppeteer.errors` and `puppeteer.devices [1]. This is a breaking change
but one that's easily mitigated. We've said that we don't consider
changes to our folder/file structure a breaking change, but we can't
really do that if we have these two top level files that we've
documented.
[1]: e3abb0aa32 (diff-522b24108d7446af4c59873472a90444)
Just one was used externally and I wrapped that up in a method. I think
it's a useful method to provide (I can imagine wanting to know if JS is
enabled on a page) so I think there's no harm here (I'd rather that then
have JSHandle reach into a private variable).
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.
