Coming from which

bellpull is a which alternative — for npm's which package, node-which — that you adopt by changing one import. bellpull/node-which is node-which 7's API, and node-which's own test suite is the grade.

Migrate from which in one import

- import which from 'which';
+ import which from 'bellpull/node-which';

Everything else stays: which(cmd, options?) returns a promise, which.sync(cmd, options?) returns the answer, and the options are node-which's — all, nothrow, path, pathExt, delimiter. A miss throws node-which's error, not found: <cmd> with code: 'ENOENT', or returns null under nothrow. So do its search rules: a command with a slash is checked as given, Windows searches the working directory first and tries PATHEXT's extensions, and a quoted PATH part is unquoted.

Two things are not carried. node-which's which command-line binary is not shipped — this is the library. And which() runs the same search as which.sync() and hands it back as a promise, rather than walking the filesystem asynchronously.

Mind the neighbouring subpath: bellpull/which is not the drop-in. It is bellpull's own resolver, with a different shape — see below.

Is bellpull compatible with which?

Graded, not claimed. node-which's own suite, vendored at 7.0.0 and unmodified apart from the import specifier, runs against bellpull/node-which beside a control that runs it against real node-which:

From Compatibility, which npm run compat:page generates from the oracle's last run; that page is the authority, and its front-end column reads bellpull because the row's import is composed onto the package root as bellpull/node-which. Five is the suite's count of top-level tests; each runs its assertions under both posix and win32 and through both which() and which.sync(). The suite's test/bin.js, which spawns node-which's CLI, is not graded, because the CLI is not shipped.

What you gain over which

• Zero dependencies. which 7.0.0 depends on isexe.
• The PATH entry that answered. bellpull/which returns where the binary is and which PATH entry found it — the fact every "two nodes on this machine" investigation starts by reconstructing with echo $PATH.
• An empty PATH entry is not the current directory. POSIX reads /usr/bin: as including .; bellpull's resolver skips empty and relative entries, and searchPath() lists each one with the reason. The drop-in keeps node-which's behaviour here, so this is a reason to move to the resolver.
• The answer is always absolute, and the resolver reads no global: the environment is an argument, so a test hands it a PATH rather than mutating process.env.

import { whichSync, whichAllSync } from 'bellpull/which';

const runtime = { platform: process.platform, env: process.env, cwd: process.cwd() };
whichSync('node', { runtime });
// { path: '/opt/homebrew/bin/node', from: '/opt/homebrew/bin', ext: '' }
whichAllSync('node', { runtime }); // every match, best first

When to switch from which

• You want node-which's answers without its dependency.
• A build differs between two machines and you need to know which binary each one found.

The resolver, the run() it feeds and the resolvers plugin host are on bellpull.