pg 201, second printing, forgot to mention 'npm install express@3'

[semmypurewal]

Gregory Hill writes:

On page 201 you have:

We can copy this file (server.js) into our Twitter directory (the same one that contains
tweet_counter.js) and then modify it so that it imports our tweet counter module and
uses the counts that we’ve exported.

However once I have done this and run the server I get the following error:

module.js:340
throw err;
^
Error: Cannot find module 'express'
at Function.Module._resolveFilename (module.js:338:15)
at Function.Module._load (module.js:280:25)
at Module.require (module.js:364:17)
at require (module.js:380:17)
at Object. (/home/vagrant/app/Twitter/server.js:1:77)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Function.Module.runMain (module.js:497:10)

This is because at no point does the book say to copy/install the express module into app/Twitter/node_modules. At this point in the book we only have:

vagrant@precise32:~/app/Twitter/node_modules$ ls
ntwitter

[semmypurewal]

Added official errata for this here: http://learningwebappdev.com/errata/chapter6/2015/03/29/forgot-to-install-express.html

[mondoleo]

On a newer Vagrant VirtualBox, the following was needed:
npm install express@3 --no-bin-links