Introduction to 

 JavaScript

< HTML / CSS

JS OO >

HTML / CSS

• Markup languages
• For presenting content / data
• Static (modulo animations)

Wanted: Interactivity!

• trigger events when users click, press keys, &c
• update the page dynamically based on those events
• fetch and display new data without leaving the page

Examples

• live search filters which update as you type
• apps like maps or stock tickers
• these slides!

We should learn JavaScript!

We should invent JavaScript!

We should invent Mocha!

- Brendan Eich, 1995

We should invent LiveScript!

- Brendan Eich, 1995

Netscape

• Was a startup
• Spiked out a quick v1
• Launched an imperfect (but very popular) product
• Planned to iterate and improve over time

Wanted

Problem

The User's Machine

• users have to trust us (and conversely)
• don't have control over which browser and version is used
• browser implementations haven't always been consistent or cooperative

Today

• ECMA maintains the ECMAScript specification
  • Periodically publishes new versions
• All major browsers support reasonably recent versions
  • See caniuse.com for more details
• JavaScript is the language of the web
• JavaScript also now runs elsewhere, everywhere

For Us

For now, we'll focus on

• core parts of the language supported across all browsers
• JavaScript running in the browser

Ready?

Head to http://codepen.io/collection/XBLJxx to get started