implements promise, makes callback optional

README.md

@@ -20,6 +20,12 @@ Usage
 - `message`: text prompt for the user
 - `handler`: function to be called with the entered text
 
+or returns a promise if handler not provided:
+
+#### `promise = prompt(message)`
+
+- `promise`: promise which resolves with the entered text
+
 Example
 -------
 
@@ -33,6 +39,17 @@ prompt('enter your first name: ', function (val) {
   });
 });
 ```
+#### with promise:
+```js
+var first, last;
+prompt('enter your first name: ').then(function (val) {
+  first = val;
+  return prompt('and your last name: ');
+}).then(function (val) {
+  last = val;
+  console.log('hi, ' + first + ' ' + last + '!');
+});
+```
 
 ### Password/hidden input
 

index.js

@@ -1,5 +1,6 @@
 var tty = require('tty')
   , keypress = require('keypress')
+  , promisify = require('./promisify')
 
 function prompt (message, hideInput, cb) {
   if (typeof hideInput === 'function') {
@@ -53,7 +54,7 @@ function prompt (message, hideInput, cb) {
   var line = '';
   process.stdin.on('keypress', listen).resume();
 }
-module.exports = prompt;
+module.exports = promisify(prompt);
 
 function password (message, cb) {
   prompt(message, true, function (val) {
@@ -62,7 +63,7 @@ function password (message, cb) {
     else cb(val, function () {}); // for backwards-compatibility, fake end() callback
   });
 }
-module.exports.password = password;
+module.exports.password = promisify(password);
 
 function multi (questions, cb) {
   var idx = 0, ret = {};
@@ -113,4 +114,4 @@ function multi (questions, cb) {
     prompt(label, q.type === 'password', record);
   })();
 }
-module.exports.multi = multi;
+module.exports.multi = promisify(multi);

promisify.js

@@ -0,0 +1,17 @@
+module.exports = function promisify(fn) {
+  return function() {
+    if (typeof Promise === 'undefined')
+      return fn.apply(null, arguments);
+
+    var args = [].slice.call(arguments);
+    var cb = args[args.length - 1];
+    if (typeof cb !== 'function') {
+      return new Promise(function(resolve) {
+        args.push(resolve);
+        fn.apply(null, args);
+      });
+    } else {
+      return fn.apply(null, args);
+    }
+  }
+}