npx: add install prompt, handle options correctly

- handle previous npx options that are still possible to be handled, and
  print a warning if any deprecated/removed options are used.
- expand shorthands properly in npx command line.
- take existing npm options into account when determining placement of
  the -- argument.
- document changes from previous versions of npx.

PR-URL: #1596
Credit: @isaacs
Close: #1596
Reviewed-by: @ruyadorno

Author: isaacs

bin/npx-cli.js

@@ -6,25 +6,123 @@ const cli = require('../lib/cli.js')
 process.argv[1] = require.resolve('./npm-cli.js')
 process.argv.splice(2, 0, 'exec')
 
+// TODO: remove the affordances for removed items in npm v9
+const removedSwitches = new Set([
+  'always-spawn',
+  'ignore-existing',
+  'shell-auto-fallback'
+])
+
+const removedOpts = new Set([
+  'npm',
+  'node-arg',
+  'n'
+])
+
+const removed = new Set([
+  ...removedSwitches,
+  ...removedOpts
+])
+
+const { types, shorthands } = require('../lib/config/defaults.js')
+const npmSwitches = Object.entries(types)
+  .filter(([key, type]) => type === Boolean ||
+    (Array.isArray(type) && type.includes(Boolean)))
+  .map(([key, type]) => key)
+
+// things that don't take a value
+const switches = new Set([
+  ...removedSwitches,
+  ...npmSwitches,
+  'no-install',
+  'quiet',
+  'q',
+  'version',
+  'v',
+  'help',
+  'h'
+])
+
+// things that do take a value
+const opts = new Set([
+  ...removedOpts,
+  'package',
+  'p',
+  'cache',
+  'userconfig',
+  'call',
+  'c',
+  'shell',
+  'npm',
+  'node-arg',
+  'n'
+])
+
 // break out of loop when we find a positional argument or --
 // If we find a positional arg, we shove -- in front of it, and
 // let the normal npm cli handle the rest.
 let i
+let sawRemovedFlags = false
 for (i = 3; i < process.argv.length; i++) {
   const arg = process.argv[i]
   if (arg === '--') {
     break
   } else if (/^-/.test(arg)) {
-    // `--package foo` treated the same as `--package=foo`
-    if (!arg.includes('=')) {
-      i++
+    const [key, ...v] = arg.replace(/^-+/, '').split('=')
+
+    switch (key) {
+      case 'p':
+        process.argv[i] = ['--package', ...v].join('=')
+        break
+
+      case 'shell':
+        process.argv[i] = ['--script-shell', ...v].join('=')
+        break
+
+      case 'no-install':
+        process.argv[i] = '--yes=false'
+        break
+
+      default:
+        // resolve shorthands and run again
+        if (shorthands[key] && !removed.has(key)) {
+          const a = [...shorthands[key]]
+          if (v.length) {
+            a.push(v.join('='))
+          }
+          process.argv.splice(i, 1, ...a)
+          i--
+          continue
+        }
+        break
+    }
+
+    if (removed.has(key)) {
+      console.error(`npx: the --${key} argument has been removed.`)
+      sawRemovedFlags = true
+      process.argv.splice(i, 1)
+      i--
+    }
+
+    if (v.length === 0 && !switches.has(key) &&
+        (opts.has(key) || !/^-/.test(process.argv[i + 1]))) {
+      // value will be next argument, skip over it.
+      if (removed.has(key)) {
+        // also remove the value for the cut key.
+        process.argv.splice(i + 1, 1)
+      } else {
+        i++
+      }
     }
-    continue
   } else {
     // found a positional arg, put -- in front of it, and we're done
     process.argv.splice(i, 0, '--')
     break
   }
 }
 
+if (sawRemovedFlags) {
+  console.error('See `npm help exec` for more information')
+}
+
 cli(process)

docs/content/cli-commands/npm-exec.md

@@ -41,7 +41,10 @@ where all specified packages are available.
 
 If any requested packages are not present in the local project
 dependencies, then they are installed to a folder in the npm cache, which
-is added to the `PATH` environment variable in the executed process.
+is added to the `PATH` environment variable in the executed process.  A
+prompt is printed (which can be suppressed by providing either `--yes` or
+`--no`).
+
 Package names provided without a specifier will be matched with whatever
 version exists in the local project.  Package names with a specifier will
 only be considered a match if they have the exact same name and version as
@@ -137,6 +140,34 @@ $ npm x -c 'eslint && say "hooray, lint passed"'
 $ npx -c 'eslint && say "hooray, lint passed"'
 ```
 
+### Compatibility with Older npx Versions
+
+The `npx` binary was rewritten in npm v7.0.0, and the standalone `npx`
+package deprecated at that time.  `npx` uses the `npm exec`
+command instead of a separate argument parser and install process, with
+some affordances to maintain backwards compatibility with the arguments it
+accepted in previous versions.
+
+This resulted in some shifts in its functionality:
+
+- Any `npm` config value may be provided.
+- To prevent security and user-experience problems from mistyping package
+  names, `npx` prompts before installing anything.  Suppress this
+  prompt with the `-y` or `--yes` option.
+- The `--no-install` option is deprecated, and will be converted to `--no`.
+- Shell fallback functionality is removed, as it is not advisable.
+- The `-p` argument is a shorthand for `--parseable` in npm, but shorthand
+  for `--package` in npx.  This is maintained, but only for the `npx`
+  executable.
+- The `--ignore-existing` option is removed.  Locally installed bins are
+  always present in the executed process `PATH`.
+- The `--npm` option is removed.  `npx` will always use the `npm` it ships
+  with.
+- The `--node-arg` and `-n` options are removed.
+- The `--always-spawn` option is redundant, and thus removed.
+- The `--shell` option is replaced with `--script-shell`, but maintained
+  in the `npx` executable for backwards compatibility.
+
 ### See Also
 
 * [npm run-script](/cli-commands/run-script)

docs/content/cli-commands/npx.md

@@ -41,7 +41,10 @@ where all specified packages are available.
 
 If any requested packages are not present in the local project
 dependencies, then they are installed to a folder in the npm cache, which
-is added to the `PATH` environment variable in the executed process.
+is added to the `PATH` environment variable in the executed process.  A
+prompt is printed (which can be suppressed by providing either `--yes` or
+`--no`).
+
 Package names provided without a specifier will be matched with whatever
 version exists in the local project.  Package names with a specifier will
 only be considered a match if they have the exact same name and version as
@@ -137,6 +140,34 @@ $ npm x -c 'eslint && say "hooray, lint passed"'
 $ npx -c 'eslint && say "hooray, lint passed"'
 ```
 
+### Compatibility with Older npx Versions
+
+The `npx` binary was rewritten in npm v7.0.0, and the standalone `npx`
+package deprecated at that time.  `npx` uses the `npm exec`
+command instead of a separate argument parser and install process, with
+some affordances to maintain backwards compatibility with the arguments it
+accepted in previous versions.
+
+This resulted in some shifts in its functionality:
+
+- Any `npm` config value may be provided.
+- To prevent security and user-experience problems from mistyping package
+  names, `npx` prompts before installing anything.  Suppress this
+  prompt with the `-y` or `--yes` option.
+- The `--no-install` option is deprecated, and will be converted to `--no`.
+- Shell fallback functionality is removed, as it is not advisable.
+- The `-p` argument is a shorthand for `--parseable` in npm, but shorthand
+  for `--package` in npx.  This is maintained, but only for the `npx`
+  executable.
+- The `--ignore-existing` option is removed.  Locally installed bins are
+  always present in the executed process `PATH`.
+- The `--npm` option is removed.  `npx` will always use the `npm` it ships
+  with.
+- The `--node-arg` and `-n` options are removed.
+- The `--always-spawn` option is redundant, and thus removed.
+- The `--shell` option is replaced with `--script-shell`, but maintained
+  in the `npx` executable for backwards compatibility.
+
 ### See Also
 
 * [npm run-script](/cli-commands/run-script)

lib/config/defaults.js

@@ -311,7 +311,7 @@ exports.types = {
   'ham-it-up': Boolean,
   heading: String,
   'if-present': Boolean,
-  include: [Array, 'dev', 'optional', 'peer'],
+  include: [Array, 'prod', 'dev', 'optional', 'peer'],
   'include-staged': Boolean,
   'ignore-prepublish': Boolean,
   'ignore-scripts': Boolean,
@@ -365,7 +365,7 @@ exports.types = {
   'save-prod': Boolean,
   scope: String,
   'script-shell': [null, String],
-  'scripts-prepend-node-path': [false, true, 'auto', 'warn-only'],
+  'scripts-prepend-node-path': [Boolean, 'auto', 'warn-only'],
   searchopts: String,
   searchexclude: [null, String],
   searchlimit: Number,
@@ -412,7 +412,7 @@ function getLocalAddresses () {
 }
 
 exports.shorthands = {
-  before: ['--enjoy-by'],
+  'enjoy-by': ['--before'],
   c: ['--call'],
   s: ['--loglevel', 'silent'],
   d: ['--loglevel', 'info'],

lib/config/flat-options.js

@@ -198,6 +198,9 @@ const flatOptions = npm => npm.flatOptions || Object.freeze({
   },
   userAgent: npm.config.get('user-agent'),
 
+  // yes, it's fine, just do it, jeez, stop asking
+  yes: npm.config.get('yes'),
+
   ...getScopesAndAuths(npm),
 
   // npm fund exclusive option to select an item from a funding list

lib/exec.js

@@ -6,21 +6,25 @@ const usage = usageUtil('exec',
   'Run a command from a local or remote npm package.\n\n' +
 
   'npm exec -- <pkg>[@<version>] [args...]\n' +
-  'npm exec -p <pkg>[@<version>] -- <cmd> [args...]\n' +
+  'npm exec --package=<pkg>[@<version>] -- <cmd> [args...]\n' +
   'npm exec -c \'<cmd> [args...]\'\n' +
-  'npm exec -p foo -c \'<cmd> [args...]\'\n' +
+  'npm exec --package=foo -c \'<cmd> [args...]\'\n' +
   '\n' +
   'npx <pkg>[@<specifier>] [args...]\n' +
   'npx -p <pkg>[@<specifier>] <cmd> [args...]\n' +
   'npx -c \'<cmd> [args...]\'\n' +
   'npx -p <pkg>[@<specifier>] -c \'<cmd> [args...]\'',
 
-  '\n-p <pkg> --package=<pkg> (may be specified multiple times)\n' +
+  '\n--package=<pkg> (may be specified multiple times)\n' +
+  '-p is a shorthand for --package only when using npx executable\n' +
   '-c <cmd> --call=<cmd> (may not be mixed with positional arguments)'
 )
 
 const completion = require('./utils/completion/installed-shallow.js')
 
+const { promisify } = require('util')
+const read = promisify(require('read'))
+
 // it's like this:
 //
 // npm x pkg@version <-- runs the bin named "pkg" or the only bin if only 1
@@ -118,9 +122,25 @@ const exec = async args => {
     // add installDir/node_modules/.bin to pathArr
     const add = manis.filter(mani => manifestMissing(tree, mani))
       .map(mani => mani._from)
+      .sort((a, b) => a.localeCompare(b))
 
     // no need to install if already present
     if (add.length) {
+      if (!npm.flatOptions.yes) {
+        // set -n to always say no
+        if (npm.flatOptions.yes === false) {
+          throw 'canceled'
+        }
+        const addList = add.map(a => `  ${a.replace(/@$/, '')}`)
+          .join('\n') + '\n'
+        const prompt = `Need to install the following packages:\n${
+          addList
+        }Ok to proceed? `
+        const confirm = await read({ prompt, default: 'y' })
+        if (confirm.trim().toLowerCase().charAt(0) !== 'y') {
+          throw 'canceled'
+        }
+      }
       await arb.reify({ add })
     }
     pathArr.unshift(resolve(installDir, 'node_modules/.bin'))

tap-snapshots/test-lib-config-flat-options.js-TAP.test.js

@@ -120,5 +120,6 @@ Object {
   "userAgent": "user-agent",
   "viewer": "viewer",
   "which": undefined,
+  "yes": undefined,
 }
 `