get rid of process.browser checks

It makes the tests a lot harder to understand. Not exactly sure how we would do it and how it will affect implementations, need time and help from the community to get this right. A suggestion would be to

1. check the commit history, why were the process.browser checks added in the first place?
2. if we remove them, what would the consequences be?
3. rewrite/update implementations that rely on this based in 1. and 2.

See the following comments:

• https://github.com/Level/abstract-leveldown/pull/93#issuecomment-222516453
• https://github.com/Level/abstract-leveldown/pull/93#r65093204

[vweevers]

To summarize what’s been achieved:

get rid of process.browser checks https://github.com/Level/abstract-leveldown/issues/121#issue-255063994

Done in #277 and #297.

The default _serialize* functions should be identity functions. Then serialization is truly an implementation’s choice. https://github.com/Level/abstract-leveldown/issues/121#issuecomment-328331961

Done in #277.

abstract-leveldown should have no idea of what environment it’s running in and assume nothing about serialization and similar implementation specific details. https://github.com/Level/abstract-leveldown/issues/121#issuecomment-328336205

If there are any assumptions left we’ll likely run into them when updating memdown and level-js.

If we […] implement [serialization of range options] ánd we drop support of null and undefined, then it means encodings like bytewise can’t use null or undefined as lower/upper bounds. https://github.com/Level/abstract-leveldown/issues/121#issuecomment-333527967

Range options are now serialized, and nullish values are rejected, since #277. To support bytewise and others, range options are no longer touched, and a test that assumed null meant “not defined” has been removed. In encoding-down, we should be able to remove _setupIteratorOptions.

this String(obj) is also problematic – https://github.com/Level/abstract-leveldown/issues/121#issuecomment-352260364

Solved in #277.

We also have various instances of [isTypedArray(value)] https://github.com/Level/abstract-leveldown/issues/121#issuecomment-343722989

I’ll open a new issue for the backlog.

Implementations like level.js don’t always support binary keys. […] We should move all tests that use binary keys to isolated test file(s). Those files can then be skipped by implementations if need be. https://github.com/Level/abstract-leveldown/issues/121#issuecomment-391748876

Solved in #297 (and earlier PRs) with a bufferKeys option.

[ralphtheninja]

So there’s another option (3): we achieve isomorphism through level. In a browser it’ll use level.js with encoding-down. If you use level.js by itself, you can choose to forego encoding-down.

I prefer this approach and I think @juliangruber does as well.