nextElementSibling, previousElementSibling polyfills

[NickColley]

Hey folks,

We are using nextElementSibling and previousElementSibiling polyfills that were in the polyfill-service library, but they don't seem to be in the new repo.

Is there any documentation why this is? I would be interested in adding these back to this version if you'd be interested too.

https://github.com/Financial-Times/polyfill-service/pull/1062/files#diff-b45a1197b842728cb76b624b6ba7d739

[JakeChampion]

Hi, I'm not sure how we lost those polyfills, sorry about that 😔

We would be interested in getting them added back.

Are you able to submit a pull-request which adds them?

[NickColley]

Yeah :) Do you have any guidelines or perhaps a pull request that demonstrates a good example of adding something? Otherwise I can figure it out...

[NickColley]

Found this: https://github.com/Financial-Times/polyfill-library/blob/master/.github/contributing.md

Will put together a PR :)

[JakeChampion]

Browser support:
https://developer.mozilla.org/en-US/docs/Web/API/NonDocumentTypeChildNode/nextElementSibling#Browser_Compatibility

We would create a new folder inside ./polyfills/Node/prototype named nextElementSibling and create 4 files within this folder:
polyfill.js -- The polyfill code itself
detect.js -- An expression which detects if nextElementSibling exists in the user-agent ( "nextElementSibling" in Node.prototype would be a good expression to use)
config.toml -- The configuration which states any dependencies the polyfill has on other features/polyfills and what user-agents/browsers need the polyfill
tests.js -- A test suite to prove the polyfill works correctly

The specification for the feature is here -- https://dom.spec.whatwg.org/#dom-nondocumenttypechildnode-nextelementsibling

Some tests already exist for this feature within the web-platform-tests projects, we should/could base our tests off of those ones. https://github.com/web-platform-tests/wpt/blob/master/dom/nodes/Element-nextElementSibling.html

A good folder in this project to look at if unsure about what to do would be requestIdleCallback https://github.com/Financial-Times/polyfill-library/tree/master/polyfills/requestIdleCallback which @notlee contributed.

[NickColley]

Thanks 💌

[JakeChampion]

If you have any questions, please comment on this issue and I will do my best to help :-)

[NickColley]

@JakeChampion is there any documentation on the syntax of the browser support in the toml file vs MDN. They don't seem to be aligned at the moment, I'm not sure what the wildcard indicates at the moment for example.

[NickColley]

I've opened a draft pull request that we can continue the discussion on, thanks for your help so far.

[JakeChampion]

@NickColley the string in config.toml.browsers are SemVer ranges. The * is the SemVer range for any version.