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: https://github.com/npm/cli/pull/1596
Credit: @isaacs
Close: #1596
Reviewed-by: @ruyadorno

1 files changed, 102 insertions, 4 deletions

diff --git a/bin/npx-cli.js b/bin/npx-cli.js
index dc2072ffd..716dc958e 100644
--- a/bin/npx-cli.js
+++ b/bin/npx-cli.js
@@ -6,20 +6,114 @@ 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, '--')
@@ -27,4 +121,8 @@ for (i = 3; i < process.argv.length; i++) {
   }
 }
 
+if (sawRemovedFlags) {
+  console.error('See `npm help exec` for more information')
+}
+
 cli(process)