A TGIF about CoffeeScript

TGIF about CoffeeScript @MeLi by Salvador Roibon.

Transcript

1. THANK GOD IS FRIDAY! #FRONTEND #UX #TGIF @MERCADOLIBRE
2. A TGIF ABOUT COFFEESCRIPT @sroibon
3. WHAT IS COFFEESCRIPT ? .COFFEE CoffeeScript is a little language that compiles into JavaScript. Is an attempt to expose the good parts of JavaScript in a simple way.
4. GOLDEN RULE The golden rule of CoffeeScript is: "It's just JavaScript".
5. SO...
6. SYNTAX BASICS First, the basics: CoffeeScript uses significant whitespace to delimit blocks of code. You don't need to use semicolons ; to terminate expressions. Don't use { } , use indentation. You don't need to use parentheses to invoke a function if you're passing arguments. The implicit call wraps forward to the end of the line or block expression.
7. VARIABLE DECLARACTION & COMMENTS myVar = value # ### The CoffeeScript compiler takes care to make sure that all of your variables are properly declared within lexical scope — you never need to write var yourself.
8. FUNCTIONS ->
9. Functions are defined by an optional list of parameters in parentheses, an arrow, and the function body. The empty function looks like this: ->
10. And OBJECTS { } ARRAYS [ ]
11. The CoffeeScript literals for objects and arrays look very similar to their JavaScript cousins. When each property is listed on its own line, the commas are optional. Objects may be created using indentation instead of explicit braces.
12. LEXICAL SCOPING AND VARIABLE SAFETY The CoffeeScript compiler takes care to make sure that all of your variables are properly declared within lexical scope — you never need to write var yourself.
13. CONDITIONALS/FLOW CONTROL If Else Then Unless
14. EVERYTHING IS AN EXPRESSION... at least, as much as possible. You might have noticed how even though we don't add return statements to CoffeeScript functions, they nonetheless return their final value. The CoffeeScript compiler tries to make sure that all statements in the language can be used as expressions. Watch how the return gets pushed down into each possible branch of execution in the function below.
15. OPERATORS AND ALIASES Because the == operator frequently causes undesirable coercion, is intransitive, and has a different meaning than in other languages, CoffeeScript compiles == into ===, and != into !==. In addition, is compiles into ===, and isnt into !==.
16. THE EXISTENTIAL OPERATOR It's a little difficult to check for the existence of a variable in JavaScript. if (variable) ... comes close, but fails for zero, the empty string, and false. CoffeeScript's existential operator ? returns true unless a variable is null or undefined, which makes it analogous to Ruby's nil? It can also be used for safer conditional assignment than ||= provides, for cases where you may be handling numbers or strings.
17. CLASSES @ === THIS Instead of repetitively attaching functions to a prototype, CoffeeScript provides a basic class structure that allows you to name your class, set the superclass, assign prototypal properties, and define the constructor, in a single assignable expression.
18. SUDO NPM INSTALL -G ...
19. INSTALL GLOBALLY WITH NPM: npm install -g coffee-script
20. ? WHY COFFEESCRIPT ?
21. "PROS": (and some facts about CoffeeScript) It covers up javascript's warts It reduces "empty" lines of code You type less code Javascript is way more popular than Coffeescript, at least a 6-to-1 ratio Coffeescript isn't alone — there are lots of languages that compile to Javascript Code is more readable It has BETTER syntax than plain Javascript If both JS and Coffeescript were invented right now, and were competing for marketshare, Coffeescript would win. You like JS only because it's the status quo, and you're familiar with it.
22. ? WHY NOT COFFEESCRIPT ?
23. "CONS": (and other facts about CoffeeScript) CoffeeScript is for people who hate JavaScript (What? NO!) JavaScript warts should be avoided by education and understanding of the core language Writing Eloquent JavaScript Without CoffeeScript is posible Is harder to maintain (more difficult to find people who knows the language) you need to compile it (one more step added to de development process) Javascript is more understandable, for sure...
24. DEBATE / CONCLUTIONS / QUESTIONS ?