Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
JS
Search
nctunba
March 14, 2012
Programming
11
640
JS
nctunba
March 14, 2012
Tweet
Share
More Decks by nctunba
See All by nctunba
被 Qt 快樂的玩弄
nctunba
2
390
被 Qt 快樂的玩弄 part 1
nctunba
1
290
Node - Express - Socket.io
nctunba
1
420
Python
nctunba
3
520
node
nctunba
9
50k
jQuery
nctunba
9
610
Other Decks in Programming
See All in Programming
What's new in Adaptive Android development
fornewid
0
130
202507_ADKで始めるエージェント開発の基本 〜デモを通じて紹介〜(奥田りさ)The Basics of Agent Development with ADK — A Demo-Focused Introduction
risatube
PRO
6
1.3k
MCP連携で加速するAI駆動開発/mcp integration accelerates ai-driven-development
bpstudy
0
240
Android 15以上でPDFのテキスト検索を爆速開発!
tonionagauzzi
0
180
Jakarta EE Meets AI
ivargrimstad
0
550
構造化・自動化・ガードレール - Vibe Coding実践記 -
tonegawa07
0
170
대규모 트래픽을 처리하는 프론트 개발자의 전략
maryang
0
110
kiroでゲームを作ってみた
iriikeita
0
130
CLI ツールを Go ライブラリ として再実装する理由 / Why reimplement a CLI tool as a Go library
ktr_0731
3
920
書き捨てではなく継続開発可能なコードをAIコーディングエージェントで書くために意識していること
shuyakinjo
0
130
構文解析器入門
ydah
7
2k
プロダクトという一杯を作る - プロダクトチームが味の責任を持つまでの煮込み奮闘記
hiliteeternal
0
340
Featured
See All Featured
Site-Speed That Sticks
csswizardry
10
740
Faster Mobile Websites
deanohume
308
31k
The Pragmatic Product Professional
lauravandoore
36
6.8k
Helping Users Find Their Own Way: Creating Modern Search Experiences
danielanewman
29
2.8k
Design and Strategy: How to Deal with People Who Don’t "Get" Design
morganepeng
130
19k
Fireside Chat
paigeccino
37
3.6k
Visualization
eitanlees
146
16k
Optimizing for Happiness
mojombo
379
70k
Embracing the Ebb and Flow
colly
86
4.8k
Agile that works and the tools we love
rasmusluckow
329
21k
Improving Core Web Vitals using Speculation Rules API
sergeychernyshev
18
1k
A Tale of Four Properties
chriscoyier
160
23k
Transcript
JavaScript
“The World's Most Misunderstood Programming Language” Douglas Crackford
A Re-introduction to JavaScript
has nothing to do with Java JavaScript
runs not only in web browsers JavaScript
History
1995 by Brendan Eich for Netscape LiveScript
None
“I had to be done in ten days or something
worse than JS would have happened.” Brendan Eich
base on Scheme LiveScript
renamed JavaScript LiveScript
Standardized ECMAScript
Language Overview
No compilation Interpreter Based
None
No class Prototypical Inheritance
except for null and undefined Object Everything
My dad is Scheme Functional Programming
“Lisp in C's Clothing” Douglas Crackford
None
Not my business Input/Output?
Variable & Types
Object Array Function null Number Boolean String undefined
Number
var a = 42;
The only number type is Number Number
double-precision 64-bit IEEE 754 Number
var a = 0.1; // 0.1 a = 010; //
8 a = 0xab; // 171
String
var a = 'hello world';
'qouted like this' ”double qouted” String
'string'.length // 6 'string'[2] // 'r' 'hello'.substr(0, 2) // 'he'
'hello' + 'world' // 'helloworld' 'string' + 2 // 'string2'
var a = 42; a = 'hello world';
JavaScript is loosely typed values are typed, variables are not
Boolean
var a = true;
true & false Boolean
'123' == 123 // true '123' === 123 // false
Content equality ==
Object identity ===
Null
var a = null; // null
Nothing Exists but nothing Null
Undefined
var a; // undefined
Not even nothing Undefined
var a; // undefined a = 5; // 5
Everything in JavaScript is undefined Until you assign something to
it
[ ] Array
var a = [4, 5, 6];
Just a list Array
var a = [4, true, 'hello']; a[0] // 4 a[3]
// undefined
var a = [4, 5, [6, 7]]; a[2] // [6,
7] a.push(7) // a → [4, 5, [6, 7], 7]
var a = [4, 5, , 6]; a.length // 4
a.toString() // '4,5,undefined,6'
{ } Object
var a = {};
Hash table Object
var bob = { name: 'bob', Job: 'teacher', age: 36
};
Name-value pair { name: value } Object
var bob = { name: 'bob' };
dynamic Object
var bob = { name: 'bob' }; bob.hair = 'brown';
bob['hair'] = 'brown';
bob.hair; // 'brown' bob['name']; // 'Bob' Bob.banana; // undefined
delete bob.hair; delete bob['name']; // bob → {};
var alice = { name: 'alice', pet: { cat: 'bob',
fish: ['a', 'b'] } }; alice.pet.fish[0] // 'a'
Now, what've we got?
JSON JS Object Notation
lightweight text-based human-readable
var alice = { name: 'alice', pet: { cat: 'bob',
fish: ['a', 'b'] } };
None
Function
var lambda = function () {};
value Function
var a = function () {}, b = 5, c
= function () { // ... };
Invoke using () Function
var five = function () { return 5; }; five;
// undefined five(); // 5
Always return Function
var void = function () { // ... }; var
a = void(); // a → undefined
Higher-order (a.k.a fantastic) Function
var chef = function (recipe, ingr) { return recipe(ingr); };
var pie = function (ingr) { return ingr + ' pie'; }; chef(pie, 'apple'); // 'apple pie'
Mom, I'm passing FUNCTIONS!!
var grandma = function () { return function () {
Return 'lol'; }; }; grandma()(); // 'lol'
Closure Function
var add = function (a, b) { return a +
b; };
var addHalf = function (a) { return function (b) {
return a + b; }; }; var add4 = addHalf(4); add4(5); // 9;
Arguments Function
var addFirstThree = function () { return arguments[0] + arguments[1]
+ arguments[2]; }; Func(1, 2, 3, 2, 3); // 6;
Length Function
var func = function (a, b) { // ... };
func.length; // 2
Control Statements
C-like ; )
Scoping
var a = 2; // a → 2
var a = 2; if () { // a →
2 } // a → 2
if () { var a = 2; // a →
2 } // a → 2
var a = 2; // a → 2
No block scope
Only Functions can make scopes
var func = function () { var a = 2;
} // a → undefined
var func = function () { var a = 2;
} // a → undefined
Local variables Var
var a = 2; // a :: Local (in Global)
a = 2; // a :: Global
var func = function () { var a = 2;
// a :: Local };
var func = function () { a = 2; //
a :: Global };
Global is bad
Never drop your var Always use them
Scope Chains
Function var Closure var Global
var addHalf = function (a) { return function (b) {
return a + b; }; }; var add4 = addHalf(4); add4(5); // 9;
Constructor Function
Function as Constructor
var Cat = function () { this.name = 'Bob'; };
var bob = new Cat; Bob.name; // 'Bob'
What is this ?
var Cat = function () { this; // Cat };
var foo = { name: 'bob', miaou: function () {
this; // foo } };
var Cat = function (name) { this.name = name ||
'Bob'; }; var bob = new Cat, alice = new Cat('Alice'); bob.name; // 'Bob' alice.name; // 'Alice'
var Cat = function () { this.name = 'Bob'; this.miaou
= function () { return this.name }; }; var bob = new Cat; bob.miaou(); // 'Bob'
var Cat = function () { this.name = 'Bob'; };
Cat.prototype.miaou = function () { return this.name }; var bob = new Cat; bob.miaou(); // 'Bob'
An attribute of every object Prototype
mom Prototype
ancenstors Prototype Chain
me mom grandma
Q & A