安裝

shell> brew install node
shell> apt-get install nodejs

shell> brew install nvm

shell> curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.32.1/install.sh | bash
shell> wget -qO- https://raw.githubusercontent.com/creationix/nvm/v0.32.1/install.sh | bash
shell> echo "source ~/.nvm/nvm.sh" >> .bashrc

shell> nvm ls-remote
shell> nvm ls-remote --lts

shell> nvm install --lts
shell> nvm install --lts=argon
shell> nvm install --lts=boron
shell> nvm install v0.12.0
shell> nvm install v4.2.2
shell> nvm install v6.1.0

shell> nvm uninstall v4.2.2
shell> nvm uninstall v6.1.0

shell> nvm use --lts
shell> nvm use --lts=argon
shell> nvm use --lts=boron

shell> nvm ls
shell> nvm alias default 0.12.0
shell> nvm alias default 4.2.2
shell> nvm alias default lts/argon
shell> nvm alias default lts/boron

shell> nvm install v6.10.1 --reinstall-packages-from=v6.10.0
shell> nvm uninstall v6.10.0

shell> nvm install v7.7.4

shell> nvm install 6 --reinstall-packages-from=5
shell> nvm install v4.2 --reinstall-packages-from=iojs

參考網站：

Hello world 範例

建立名為 hello.js 的檔案，並新增下列程式碼：

console.log('Hello World!');

使用下列指令來執行應用程式：

shell> node hello.js

`變數` (`Variable`)

JavaScript 有兩個範圍：全域和區域。在函式定義之外宣告的變數就是全域變數，其值可在整個程式中存取和修改。宣告變數。在函式定義內宣告的變數則是區域變數。可以宣告變數而不使用 var 關鍵字，並為變數指派值。這稱為「隱含宣告」，但不建議使用。隱含宣告會提供全域範圍給變數。如果未初始化 var 中的變數，系統會自動指派 JavaScript 值 undefined 給此變數。下列程式碼是示範如何宣告整數變數、指派其值，然後再為其指派新值的簡單範例。

var a;
var a = 1;
var a = 0, b = 0;
var bigNumber = 1e100;
var mynumber = 99;

var u = undefined;

var myString = new String('Hello');
var mytext = 'Hello World!';

var b = new Boolean(false);
var x = new Boolean(false);
var x = false;
var myFalse = new Boolean(false);
var myboolean = true, myFalse = false;
var btrue = new Boolean(true);
var bfalse = new Boolean(false);
var F = new Boolean();
var T = new Boolean(true);
var F = new Boolean(0);
var T = new Boolean(1);

function doSomething() {}
var f = function() {};
f();
var myFunc = function() {};


var text = null;

var o = {};
var myObj = {}, myobject = { nickname: 'Jack', "registration_date": new Date(1995, 11, 25), "privileged_user": true };
var object = {
  someMethod: function() {}
};

var myarray = [], someArray = [ 1, 2, 3 ];

var greeting = "Hello, World!";

var index;  
var name = "Thomas Jefferson";  
var answer = 42, counter, numpages = 10;  
var myarray = new Array();

var mynumber = 99;
console.log(`my favorite number is: ${mynumber}`);

`常數` (`Constant`)

常數會使用 const 宣告在這個範例中，常數 MY_FAV 永遠會是 7

// define MY_FAV as a constant and give it the value 7
const MY_FAV = 7;

MY_FAV = 20;

// will print 7
console.log("my favorite number is: " + MY_FAV);

var MY_FAV = 20; 

// MY_FAV is still 7
console.log("my favorite number is " + MY_FAV);

const months = 12, weeks = 52, days = 365;
const daysPerWeek = days / weeks;
const daysPerMonth = days / months;

const speedLimit = 55;
const pi = 3.14159265358979323846264338327950;
const Pi = 3.14159;
const SpeedOfLight = 300000; // km per sec.

範例

var radius = 5.3; // Radius 半徑
const pi = 3.14159265358979323846264338327950; // PI 圓周率
var area = pi * (radius * radius); // Area 面積

宣告區塊範圍變數。「區域變數」(Local Variable) 使用 let 來宣告變數，其範圍限於宣告所在的區塊。

'use strict';

function varTest() {
  var x = 31;
  if (true) {
    var x = 71;  // same variable!
    console.log(x);  // 71
  }
  console.log(x);  // 71
}

function letTest() {
  let x = 31;
  if (true) {
    let x = 71;  // different variable
    console.log(x);  // 71
  }
  console.log(x);  // 31
}

參考網站：

Events

var EventEmitter = require('events').EventEmitter;
var myEmitter = new EventEmitter(); 

myEmitter.on('event', function () {
  console.log('an event occurred!'); 
});

myEmitter.emit('event');

const EventEmitter = require('events');
class MyEmitter extends EventEmitter {}
const myEmitter = new MyEmitter();

myEmitter.on('event', () => {
  console.log('an event occurred!');
});

setTimeout(function() {
  myEmitter.emit('event');
}, 1000);

var EventEmitter = require('events').EventEmitter;
var myEmitter = new EventEmitter();

myEmitter.on('hello', function (arg1, arg2) {
    console.log(arg1 + ' ' + arg2);
});

myEmitter.emit('hello', 'Hello', 'World');

var EventEmitter = require('events').EventEmitter;
var myEmitter = new EventEmitter();

myEmitter.on('sayHello', function(name) {
  console.log("Hello" + " " + name);
});

myEmitter.emit('sayHello', 'Eric');

Arrow functions

var a = [
  'Hydrogen',
  'Helium',
  'Lithium',
  'Beryllium'
];

var a2 = a.map(function(s) { return s.length; });
console.log(a2); // logs [8, 6, 7, 9]

var a3 = a.map(s => s.length);
console.log(a3); // logs [8, 6, 7, 9]

var myObj = {
  nickname: "Jack",
  registration_date: new Date(1995, 11, 25)
}

var {
  nickname,
  registration_date
} = myObj;

console.log(nickname);
console.log(registration_date);

var nickname = 'Jack';
var registration_date = new Date(1995, 11, 25);
var myObj = {nickname, registration_date};

console.log(myObj);

參考網站：

events

for...of

let iterable = [10, 20, 30];

for (let value of iterable) {
  value += 1;
  console.log(value);
}
// 11
// 21
// 31

參考網站：

for...of

coding-style

coding-style

`Comma First`

var magicWords = [ 'abracadabra'
                 , 'gesundheit'
                 , 'ventrilo'
                 ]
  , spells = { 'fireball' : function () { setOnFire() }
             , 'water' : function () { putOut() }
             }
  , a = 1
  , b = 'abc'
  , etc
  , somethingElse

`Quotes`

var ok = 'String contains "double" quotes'
var alsoOk = "String contains 'single' quotes or apostrophe"

Functions 函數 函式
Properties 屬性
Methods 方法
Class 類別
lowerCamelCase → Objects Functions Methods Properties
UpperCamelCase → Class
all-lower-hyphen-css-case → FileName Config
CAPS_SNAKE_CASE

參考網站：

費氏數列

費氏數列
費波那契數列

F~0~ = 0 F~1~ = 1 F~n~ = F~n-1~ + F~n-2~ (n≧2)

用文字來說，就是費氏數列由0和1開始，之後的費波那契系數就是由之前的兩數相加而得出。首幾個費波那契系數是： 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233……

2÷1=2
3÷2=1.5
5÷3=1.666666667
8÷5=1.6
13÷8=1.625
21÷13=1.615384615
34÷21=1.619047619
55÷34=1.617647059
89÷55=1.618181818
144÷89=1.617977528
233÷144=1.618055556
377÷233=1.618025751
610÷377=1.618037135

1×1=1
2×2=4
3×3=9
5×5=25
8×8=64
13×13=169
21×21=441

0.618:1=1:1.618 1-0.618=0.382

function fibonacci(num){
  var fn1 = 0;
  var fn2 = 1;
  var tmp;
  while (num >= 0){
    tmp = fn2;
    fn2 = fn2 + fn1;
    fn1 = tmp;
    num--;
  }
  return fn1;
}

function* fibonacci() {
  var fn1 = 0;
  var fn2 = 1;
  while (true) {  
    var current = fn1;
    fn1 = fn2;
    fn2 = current + fn1;
    yield current;
  }
}

var sequence = fibonacci();
console.log(sequence.next().value);     // 0
console.log(sequence.next().value);     // 1
console.log(sequence.next().value);     // 1
console.log(sequence.next().value);     // 2
console.log(sequence.next().value);     // 3
console.log(sequence.next().value);     // 5
console.log(sequence.next().value);     // 8
console.log(sequence.next().value);     // 8
console.log(sequence.next().value);     // 13
console.log(sequence.next().value);     // 21

入門

安裝

參考網站：

Hello world 範例

`變數` (`Variable`)

`常數` (`Constant`)

參考網站：

Events

Arrow functions

參考網站：

for...of

參考網站：

coding-style

`Comma First`

`Quotes`

參考網站：

費氏數列

results matching ""

No results matching ""

安裝

參考網站：

Hello world 範例

變數 (Variable)

常數 (Constant)

參考網站：

Events

Arrow functions

參考網站：

for...of

參考網站：

coding-style

Comma First

Quotes

參考網站：

費氏數列

results matching ""

No results matching ""

`變數` (`Variable`)

`常數` (`Constant`)

`Comma First`

`Quotes`