help: Implement new help message like did-you-mean

When user makes typo, npm display command list when there are similar commands.

PR-URL: https://github.com/npm/npm/pull/10382
Fixes: #4324
Credit: @watilde
Reviewed-By: @iarna

2 files changed, 26 insertions, 0 deletions

diff --git a/lib/help.js b/lib/help.js
index 9763d5fcc..64c80f787 100644
--- a/lib/help.js
+++ b/lib/help.js
@@ -12,6 +12,7 @@ var npm = require('./npm.js')
 var log = require('npmlog')
 var opener = require('opener')
 var glob = require('glob')
+var didYouMean = require('./utils/did-you-mean')
 var cmdList = require('./config/cmd-list').cmdList
 var shorthands = require('./config/cmd-list').shorthands
 var commands = cmdList.concat(Object.keys(shorthands))
@@ -181,6 +182,11 @@ function npmUsage (valid, cb) {
     '',
     'npm@' + npm.version + ' ' + path.dirname(__dirname)
   ].join('\n'))
+
+  if (npm.argv.length > 1) {
+    didYouMean(npm.argv[1], commands)
+  }
+
   cb(valid)
 }
 
diff --git a/lib/utils/did-you-mean.js b/lib/utils/did-you-mean.js
new file mode 100644
index 000000000..8e72dde5f
--- /dev/null
+++ b/lib/utils/did-you-mean.js
@@ -0,0 +1,20 @@
+var meant = require('meant')
+var output = require('./output.js')
+
+function didYouMean (scmd, commands) {
+  var bestSimilarity = meant(scmd, commands).map(function (str) {
+    return '    ' + str
+  })
+
+  if (bestSimilarity.length === 0) return
+  if (bestSimilarity.length === 1) {
+    output('\nDid you mean this?\n' + bestSimilarity[0])
+  } else {
+    output(
+      ['\nDid you mean one of these?']
+        .concat(bestSimilarity.slice(0, 3)).join('\n')
+    )
+  }
+}
+
+module.exports = didYouMean