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Topics Covered

  • Review of how we manage 3rd party modules in the browser
  • Convert a simple script from the web to node
  • Using NPM to install our dependencies rather than a CDN via script tag

Example Code

In Node.js we don’t have access to the DOM so we can not load our 3rd party modules with a CDN. In Node.js we need to use NPM which is a registry hosting 3rd party JavaScript which allows us to download locally to run within our Node.js environment.

From Browser


<!DOCTYPE html>
  <main>Hello World</main>
  <script src=""></script>
  <script src="app.js"></script>


// <script src="underscore.js"> tag for underscore
var instructors = ['PatrickJS', 'Scott Moss', 'Mike Adams'];
_.each(instructors, function(person) {
  console.log('Hello', person);


To Node.js


var _ = require('underscore');
_.each(instructors, function(person) {
  console.log('Hello', person); 

TypeScript - Static Properties is not loading............
Viktoriya Mancheva
Hey guys, the previous page - TypeScript - Static Properties is not loading... Could you please fix this? Thank you.
Roberto da Conceicao
It is not loading.
Skinny Tod
Too many assumptions here:
– that we know what "underscore.js" is and why it is needed(e.g. "you can see we are using the each from underscore" – huh?)
–that we know what "require" does and how it relates to node.js
Vani Ananthuni
i’m getting these errors after installing underscore. any idea why?
node app.js
SyntaxError: Unexpected identifier
at Object.exports.createScript (vm.js:24:10)
at REPLServer.defaultEval (repl.js:235:25)
at bound (domain.js:287:14)
at REPLServer.runBound [as eval] (domain.js:300:12)
at REPLServer. (repl.js:431:12)
at emitOne (events.js:82:20)
at REPLServer.emit (events.js:169:7)
at REPLServer.Interface._onLine (readline.js:211:10)
at REPLServer.Interface._line (readline.js:550:8)
at REPLServer.Interface._ttyWrite (readline.js:827:14)
Travis Ueki
Can you upload a screenshot of your package.json file?
Peter Šupina
In the example code "To Node.js", this line of code is missing:

var instructors = ['PatrickJS', 'Scott Moss', 'Mike Adams'];
Lamont Thompkins
Hardly taking a breath, the speaker spoke so fast that I had to play the video several times to understand what was said. I understand that time is important, but so is comprehension.
arnold sanders
Seems like a simple process. Go into the project folder. Run npm install x . And in the file that you want the library in, require it inside of a variable. Nice! I really appreciate how short these videos are. Its straight to the point.