Add path.getPrevSibling, path.getNextSibling, etc.

[kangax]

We have quite a few cases of path.parentPath.getSibling(path.parentPath.key + 1) in Babili's DCE.

It would be nice if Babel provided basic traversal methods like getPrevSibling(), getNextSibling(), forEachPrevSibling(), forEachNextSibling(), etc.

Naming subject to change, of course.

---

EDIT by @hzoo

• Comment below you are going to do this (for others to know)
• Read CONTRIBUTING.md
• This can be done on master
• remember to run make build after a source code change or better just run make watch in another terminal window to auto run babel while you are developing
• Check out the handbook if you need more context into what a "sibling" is. Basically it's like the same idea with a DOM sibling ($("a").siblings) but instead its an AST node sibling.

---

• modify babel-traverse/src/path/family.js and add the methods shown above ^ https://github.com/babel/babel/blob/master/packages/babel-traverse/src/path/family.js#L60-L67
• add tests in https://github.com/babel/babel/blob/master/packages/babel-traverse/test/family.js

[babel-bot]

Hey @kangax! We really appreciate you taking the time to report an issue. The collaborators
on this project attempt to help as many people as possible, but we're a limited number of volunteers,
so it's possible this won't be addressed swiftly.

If you need any help, or just have general Babel or JavaScript questions, we have a vibrant Slack
community that typically always has someone willing to help. You can sign-up here
for an invite.

[hzoo]

I like it! Names seem fine to me but maybe someone else has a better idea. We should just have something like jQuery haha https://api.jquery.com/category/traversing/tree-traversal/.

[kangax]

Seems like a nice beginner-friendly task so I'm marking it as such.

[hzoo]

Yep! I'l update the issue for that stuff.

If someone wants to chime in on a good name though..

[chitchu]

Hi @kangax, @hzoo

If you don't mind I'll pick this one up.

I do have a suggestion. Instead of getNextSibling(), getPrevSibling(), would method chaining be better syntax wise? ie getSibling().next(), getSibling().prev(), getSibling().prev().prev().next()

[kangax]

@chitchu chaining would work automatically since the method will be defined on a path and will return another path (or null/undefined).

[chitchu]

@kangax I misunderstood what getSibling does. That makes it clear then.