npm: Support two-factor authentication: ask for a one-time password

lib/npm.js

@@ -62,7 +62,17 @@ module.exports = function( Release ) {
 			return tags;
 		},
 
-		_publishNpm: function() {
+		// Ask for a one-time password for 2FA-enabled accounts;
+		// returns OTP as string if provided, undefined otherwise.
+		_getNpmOtp: async function() {
+			var otp = await Release.promptFor(
+				"Enter one-time password if you have 2FA enabled and press Enter.\n" +
+				"Otherwise, just press Enter." );
+
+			return otp || undefined;
+		},
+
+		_publishNpm: async function() {
 			if ( !Release.npmPublish ) {
 				return;
 			}
@@ -71,16 +81,19 @@ module.exports = function( Release ) {
 
 			var npmPublish,
 				newVersion = Release.readPackage().name + "@" + Release.newVersion,
-				safety = Release.isTest ? " --dry-run" : "",
-				npmTags = Release.npmTags();
+				safety = Release.isTest ? "--dry-run" : "",
+				npmTags = Release.npmTags(),
+				otp = await Release._getNpmOtp();
 
 			if ( Release.isTest ) {
 				console.log( "Actual release would now publish to npm using:" );
 			} else {
 				console.log( "Publishing to npm, running:" );
 			}
 
-			npmPublish = "npm publish" + safety + " --tag " + npmTags.pop();
+			npmPublish = `npm publish ${ safety } ${
+				otp ? `--otp ${ otp }` : ""
+			} --tag ${ npmTags.pop() }`;
 			console.log( "  " + chalk.cyan( npmPublish ) );
 			Release.exec( npmPublish );
 

lib/prompt.js

@@ -1,6 +1,7 @@
 "use strict";
 
-var chalk = require( "chalk" );
+var chalk = require( "chalk" ),
+	{ prompt } = require( "enquirer" );
 
 module.exports = function( Release ) {
 
@@ -13,6 +14,17 @@ Release.define( {
 		process.stdin.resume();
 	},
 
+	// prints a given message, provide back the entered string after trimming.
+	// Also, returns a promise resolving to that string.
+	promptFor: async function( message ) {
+		var { input } = await prompt( {
+			type: "input",
+			name: "input",
+			message
+		} );
+		return input;
+	},
+
 	confirm: function( fn ) {
 		console.log( chalk.yellow( "Press enter to continue, or ctrl+c to cancel." ) );
 		Release.prompt( fn );