2015-05-14

JavaScript 學習筆記

把一些比較特別需要記的記錄下來。

  • JavaScript 跟 Java 沒關係，雖然 Netscape 想讓他們看起來有關係。 XD
  • JavaScript 是一個直譯式、動態型別、弱型別、原型導向的程式語言。

Data Type

Primitive Data Type

  • Number
    沒有區分 Interger 與 Float point number
  • String
    Single qoute or double qoute are all acceptable.
  • Boolean
    Keyword: true flalse
  • Undefined
  • Null

    Composite Data Type

  • Array
  • Object

Can be nested, contain other composite data type within it.

Syntax

Operator

  • ===: equal operator
  • !==: not equal operator

Basic Input/Output

  • console.log()
  • confirm()
  • prompt()

Variable Declearation & Definiton

  • var variableName;
  • var variableName = value;

Array Declearation & Definiton

var emptyArray = [];
var arrayName = [data, data, data];
var mixed = [34, "candy", "blue", 11];
var nested = [ [1, 2, 3], ["Alice", "Bob"] ];

Object Declearation & Definiton

var myObject = {};
var myObject = new Object();

Object members can be access by useing member name string as inedx.

var myObject = {
    name: "Yiguo",
    "birthday": "0628",
    getName: function() { console.log(name); },
    getBirthday: function() { console.log(birthday); }
};
console.log( myObject["name"] );
console.log( myObject.birthday );
myObject.getName();
myObject["getName"]();

Object constructer can be defined just like a function.

function Person(name,age) {
  this.name = name;
  this.age = age;
}

var bob = new Person("Bob Smith", 30);
var susan = new Person("Susan Jordan", 25);

Function Declearation & Definiton

function myFunction(a, b) {
    return a * b;
}

A JavaScript function can also be defined using an expression, and function expression can be stored in a variable. After a function expression has been stored in a variable, the variable can be used as a function.

var x = function (a, b) {return a * b};
var z = x(4, 3);

Control Flow

for in loop

for in loop can be used to loop throught the menber of a object (and array).

var array = [1, 2, 3, 4];
var object = { name:"Yiguo", age:24 }
for ( i in array ) { array[i] += 1; }
for ( x in object ) { console.log( object[x] ); }
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