Introduce version alias for current node version and project pined version

README.md

@@ -5,7 +5,10 @@
 [![Twitter](https://img.shields.io/badge/%E2%80%8B-twitter-4cc61e.svg?logo=twitter)](https://twitter.com/intent/follow?screen_name=ehmicky)
 [![Medium](https://img.shields.io/badge/%E2%80%8B-medium-4cc61e.svg?logo=medium)](https://medium.com/@ehmicky)
 
-Normalize and validate Node.js versions
+Normalize and validate Node.js versions.
+
+Can guess the current project's version using its `.nvmrc` if you use supported
+[aliases](#supported-aliases).
 
 # Example
 
@@ -21,6 +24,8 @@ await normalizeNodeVersion('v8.5.0') // '8.5.0'
 await normalizeNodeVersion('8.5.2') // Error: Invalid Node version
 await normalizeNodeVersion('<7') // '6.17.1'
 await normalizeNodeVersion('*') // Latest Node version, e.g. '12.8.0'
+await normalizeNodeVersion('_') // Node version used by current process
+await normalizeNodeVersion('.') // Node version from a '.nvmrc', '.node-version' or '.naverc' file in the current directory or any parent directory
 await normalizeNodeVersion('not_a_version') // Error: Invalid Node version
 
 // All available options
@@ -64,6 +69,24 @@ Base URL. Can be customized (for example `https://npm.taobao.org/mirrors/node`).
 The following environment variables can also be used: `NODE_MIRROR`,
 `NVM_NODEJS_ORG_MIRROR`, `N_NODE_MIRROR` or `NODIST_NODE_MIRROR`.
 
+#### cwd
+
+_Type_: `string`\
+_Default_: `process.cwd()`
+
+Start from this directory when looking for a Node.js version file when using the
+`.` alias (`.node-version`, `.nvmrc` or `.naverc`).
+
+### Supported aliases
+
+`normalizeNodeVersion` supports some Node version aliases you can use as
+`versionRange`:
+
+- `_` : Node version used by the current process
+- `.` : Node version from a `.nvmrc`, `.node-version` or `.naverc` file in the
+  current directory or any parent directory. If no version file is found, it
+  will default to the current process version.
+
 # See also
 
 - [`nve`](https://github.com/ehmicky/nve): Run a specific Node.js version (CLI)

package.json

@@ -52,6 +52,7 @@
   "dependencies": {
     "all-node-versions": "^6.0.1",
     "core-js": "^3.6.4",
+    "find-up": "^4.1.0",
     "global-cache-dir": "^2.0.0",
     "semver": "^7.1.3",
     "write-file-atomic": "^3.0.3"

src/aliases.js

@@ -0,0 +1,32 @@
+import { promises as fs } from 'fs'
+import { version as processVersion } from 'process'
+
+import findUp from 'find-up'
+
+const NODE_VERSION_ALIAS = '.'
+const NODE_VERSION_FILES = ['.node-version', '.nvmrc', '.naverc']
+
+const CURRENT_NODE_ALIAS = '_'
+
+const resolveNodeVersionAlias = async ({ cwd }) => {
+  const nodeVersionFile = await findUp(NODE_VERSION_FILES, { cwd })
+  if (nodeVersionFile === undefined) return
+
+  const nodeVersionFileContent = await fs.readFile(nodeVersionFile, 'utf-8')
+  return nodeVersionFileContent.trim()
+}
+
+export const resolveVersionRangeAlias = async function (
+  versionRange,
+  { cwd } = {},
+) {
+  if (versionRange === CURRENT_NODE_ALIAS) return processVersion
+
+  if (versionRange === NODE_VERSION_ALIAS) {
+    const resolvedVersion = await resolveNodeVersionAlias({ cwd })
+
+    return resolvedVersion || processVersion
+  }
+
+  return versionRange
+}

src/main.js

@@ -1,14 +1,19 @@
 import allNodeVersions from 'all-node-versions'
 import { maxSatisfying } from 'semver'
 
+import { resolveVersionRangeAlias } from './aliases.js'
 import { getCachedVersions, cacheVersions } from './cache.js'
 import { handleOfflineError } from './offline.js'
 
 // Retrieve the Node version matching a specific `versionRange`
 const normalizeNodeVersion = async function (versionRange, opts) {
-  const versions = await getVersions(versionRange, opts)
+  const resolvedVersionRange = await resolveVersionRangeAlias(
+    versionRange,
+    opts,
+  )
+  const versions = await getVersions(resolvedVersionRange, opts)
 
-  const version = maxSatisfying(versions, versionRange)
+  const version = maxSatisfying(versions, resolvedVersionRange)
 
   if (version === null) {
     throw new Error(`Invalid Node version: ${versionRange}`)