Adrian Liaw

CoffeeScript 是什麼??

CoffeeScript is a little language that compiles into JavaScript.

CoffeeScript 是一個可以轉換成JavaScript的小型語言

認識CoffeeScript的作者

Jeremy Ashkenas

紐約時報圖形部門
Backbone.js 作者
Underscore.js 作者
CoffeeScript 作者

進入正題

CoffeeScript 的原則

It's just JavaScript

它就只是JavaScript
編譯器將CoffeeScript的程式一對一的轉換成JavaScript
沒有所謂的"直譯器(interpreter)"
你可以使用任何現有的JavaScript函式庫
編譯出來的JavaScript是可讀性高的
產生出的JavaScript有時比手寫的執行效率還高

為什麼要使用CoffeeScript

Why CoffeeScript

程式碼很乾淨
可以省掉一半的程式碼
程式碼好讀，比較接近自然語言
語法似Python, Ruby, Haskell
人的時間貴於機器的時間

實務上來看

使用縮排區分程式區塊
省略不必要的括弧和分號
增加了"class"語法 (OOP)
list comprehension (串列綜合運算)
自動處理區域變數問題

而JavaScript...

用大括弧來區分，到處都是大括弧
一大堆有的沒的大括弧中括弧小括弧和分號
一個是定義function，而另一個是定義function
先產生一個空白的Array，然後用for loop一個個加
定義變數用var不用var傻傻分不清楚

相信大家還是聽不懂

還是動手做比較快

Variables

myNumber = 10
myBool   = true
myString = "Hello World"

var myBool, myNumber, myString;

myNumber = 10;

myBool = true;

myString = "Hello World";

Function Calls

console.log "Hello"

Math.pow 2, 3

myDiv = $ "#my-div"

var myDiv;

console.log("Hello");

Math.pow(2, 3);

myDiv = $("#my-div");

Functions

square        = (x)    -> x * x
double_double = (x, y) -> (x + y) * 2

helloWorld = ->
  message = "Hello World"
  console.log message

var double_double, helloWorld, square;

square = function(x) {
  return x * x;
};

double_double = function(x, y) {
  return (x + y) * 2;
};

helloWorld = function() {
  var message;
  message = "Hello World";
  return console.log(message);
};

Conditions

if a < b
  unless c is b
    if c isnt d
      console.log "FOO"
    else
      console.log "BAR"

if (a < b) {
  if (c !== b) {
    if (c !== d) {
      console.log("FOO");
    } else {
      console.log("BAR");
    }
  }
}

Comments

# This is a "line comment"

###
This is a "block comment"
###


/*
This is a "block comment"
 */

小練習1: 費氏數列

Fibonacci Time!

小練習1: 費式數列的第n項

fib(n) = fib(n-1) + fib(n - 2)

f i b (n) = f i b (n - 1) + f i b (n - 2)

fib (0) = 1, fib(1) = 1

f i b (0) = 1, f i b (1) = 1

[1, 1, 2, 3, 5, 8, 13, 21, 34, 55, ...]

結果應該要長這樣

coffee> fib 5
8
coffee> fib 10
89
coffee> fib 0
1
coffee> fib 16
1597

String Formatting

n = 11
m = 3

console.log "#{n} powered by #{m} is #{Math.pow n, m}"

var m, n;

n = 11;

m = 3;

console.log(n + " powered by " + m + " is " + (Math.pow(n, m)));

Multiline Strings

agileManifesto = 
"""
Individuals and interactions over processes and tools
Working software over comprehensive documentation
Customer collaboration over contract negotiation
Responding to change over following a plan
"""

var agileManifesto;

agileManifesto = "Individuals and interactions over processes and tools\nWorking software over comprehensive documentation\nCustomer collaboration over contract negotiation\nResponding to change over following a plan";

Arrays

myList = [1, 2, 3, 4]

coders = [
  "Adrian Liaw"
  "Michael Pan"
  "Jeffrey Lee"
]

var coders, myList;

myList = [1, 2, 3, 4];

coders = ["Adrian Liaw", "Michael Pan", "Jeffrey Lee"];

Slices / Ranges

numbers = [1..10]

start = numbers[..2]

middle = numbers[3...-2]

end = numbers[-2..]

copy = numbers[..]

var copy, end, middle, numbers, start;

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

start = numbers.slice(0, 3);

middle = numbers.slice(3, -2);

end = numbers.slice(-2);

copy = numbers.slice(0);

Objects

adrianliaw =
  name: "Adrian Liaw"
  age:  14
  sex:  "Male"

var adrianliaw;

adrianliaw = {
  name: "Adrian Liaw",
  age: 14,
  sex: "Male"
};

While Loops

while true
  console.log "Infinity Loop!"

until false
  console.log "Infinity Loop!"

buy thing while supply > demand

eat food until full

while (true) {
  console.log("Infinity Loop!");
}

while (!false) {
  console.log("Infinity Loop!");
}

while (supply > demand) {
  buy(thing);
}

while (!full) {
  eat(food);
}

For Loops

lunch = ["beef", "pasta", "apple"]

for food in lunch
  eat food
  console.log "Finished #{food}"

myObj =
  one: 1
  two: 2
  three: 3

for num, i of myObj
  console.log num, i

var food, i, lunch, myObj, num, _i, _len;


lunch = ["beef", "pasta", "apple"];

for (_i = 0, _len = lunch.length; _i < _len; _i++) {
  food = lunch[_i];
  eat(food);
  console.log("Finished " + food);
}

myObj = {
  one: 1,
  two: 2,
  three: 3
};

for (num in myObj) {
  i = myObj[num];
  console.log(num, i);
}

Extra Operators

CoffeeScript	JavaScript
`is`	`===`
`isnt`	`!==`
`not`	`!`
`and`	`&&`
`or`	`\|\|`
`true, yes, on`	`true`
`false, no, off`	`off`

CoffeeScript	JavaScript
`@, this`	`this`
`of`	`in`
`in`	No JS equivalent
`a ** b`	`Math.pow(a, b)`
`a // b`	`Math.floor(a / b)`
`a %% b`	`(a % b + b) % b`

小練習2: 重複字串

Repeating String

在Python裡面，我們如果要反覆一個字串，可以這樣：

>>> "string" * 3

但在JavaScript裡做這樣的動作只會回傳NaN

用CoffeeScript寫一個吧！

Repeating String

定義一個function，有兩個參數，第一個是字串s，第二個是數字n，回傳s重覆n次的字串

coffee> repeat "hello", 3
'hellohellohello'

coffee> repeat "Kids Coding Studio!", 2
'Kids Coding Studio!Kids Coding Studio!'

coffee> repeat "Michael", 1
'Michael'

coffee> repeat "FooBarBaz", 0
''

小練習3: 金字塔

Pyramid

印出x層的金字塔！

coffee> pyramid 5
    *
   ***
  *****
 *******
*********
coffee> pyramid 8
       *
      ***
     *****
    *******
   *********
  ***********
 *************
***************

Array Comprehensions

什麼是Array Comprehension??

在Python裡叫"List Comprehension"

它來自數學的"Set Comprehension"

映射輸出值

變數

輸入值集合

條件

其實就等於

inputSet = [0..10]

outputSet = []

for x in inputSet

  if x ** 2 > 3

    ouputSet.push 2 * x

用Array Comprehension 來簡化

output = (2 ＊ x for x in [0..10] when x ** 2 > 3)

output = (
  2 * x \             # 映射值
  for x in [0..10] \ # 輸入值集合
  when x ** 2 > 3     # 條件
)

output = (2 * x for x in [0..10] when x ** 2 > 3)

var output, x;

output = (function() {
  var i, results;
  results = [];
  for (x = i = 0; i <= 10; x = ++i) {
    if (Math.pow(x, 2) > 3) {
      results.push(2 * x);
    }
  }
  return results;
})();

Squares

squares = (i ** 2 for i in [0..10])

[0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

Stepping

squares = (i ** 2 for i in [0..10] by 2)

[0, 4, 16, 36, 64, 100]

When

multipleOfThree = (i for i in [0..20] when i % 3 is 0)

[0, 3, 6, 9, 12, 15, 18]

Or/And

(j for j in [0..30] when j % 3 is 0 or j % 5 is 0)

[0, 3, 5, 6, 9, 10, 12, 15, 18, 20, 21, 24, 25, 27, 30]

(p for p in [0..30] when p % 3 is 0 and p % 5 isnt 0)

[3, 6, 9, 12, 18, 21, 24, 27]

小練習4: 找質數

在0~n之間有哪些質數?

coffee> primes 10
[2, 3, 5, 7]

coffee> primes 50
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47]

方法1

檢查從2~n中每一個數字能不能被任何數字(不包括1和該數)整除

2: no

3: no

4: 2

5: no

6: 2

7: no

8: 2

9: 3

Example:

primes 10

[2, 3, 5, 7]

方法2

篩法(sieve)，原始陣列為2~n，先用2過濾，把2的倍數去掉，再用3過濾，把3的倍數去掉，再用5過濾，把5的倍數去掉......

最後剩下的數字就是質數

埃拉托斯特尼篩法

sieve of Eratosthenes

FAQ

學CoffeeScript就不用學JavaScript嗎？
使用CoffeeScript可以取代JavaScript？
一定要把*.coffee編譯成*.js才能用？
用CoffeeScript需不需要把其他js全改寫？
有沒有從js轉成coffee的工具？

其他參考資料

Q&A

謝謝大家

歡迎follow我的GitHub XD

http://github.com/adrianliaw

CoffeeScript

By Adrian Liaw

CoffeeScript

1,663

Adrian Liaw

A secondary school coder from Taiwan

github.com/adrianliaw

進入正題

CoffeeScript 的原則

為什麼要使用CoffeeScript

而JavaScript...

相信大家還是聽不懂

還是動手做比較快

Variables

Function Calls

Functions

Conditions

Comments

小練習1: 費氏數列

Fibonacci Time!

String Formatting

Multiline Strings

Arrays

Slices / Ranges

Objects

While Loops

For Loops

Extra Operators

小練習2: 重複字串

Repeating String

Repeating String

小練習3: 金字塔

Pyramid

Array Comprehensions

用Array Comprehension 來簡化

Squares

Stepping

When

Or/And

小練習4: 找質數

方法1

方法2

埃拉托斯特尼篩法

更多功能...

FAQ

其他參考資料

Q&A

謝謝大家

歡迎follow我的GitHub XD

CoffeeScript

More from Adrian Liaw