Javascript学习笔记一 对象

 检索:
1 用||来填充默认值
var status = flight.status || "unknown";
2 使用&&防止TypeError
flight.equipment.model //throw "TypeError"
flight.equipment && flight.equipment.model //undefined

引用
var a={},b={},c={};
document.writeln(a===b); //false
原型
Javascript提供的实现机制：
var stooge = {
"first-name":"Jerome",
"last-name":"Howard"
};
var temp = function(){};
temp.prototype=stooge;
var another_stooge= new temp;
可以直接给Object加个方法来简化
if (typeof Object.beget !== 'function'){
Object.beget = function (o){
var F = function (){};
F.prototype = o;
return new F();
}
}
var another_stooge =Object.beget(stooge);
another_stooge["first-name"] = 'Harry';
document.writeln(another_stooge["first-name"]); //Harry
document.writeln(another_stooge["last-name"]); //Howard
document.writeln(stooge["first-name"]); //Jerome

反射
typeof可以访问原型链
document.writeln(typeof flight.toString); //function
hasOwnProperty则不行
 document.writeln(flight.hasOwnProperty('toString')); //false
枚举
使用for in枚举属性 的顺序是不确定的，而且需要使用hasOwnProperty，并使用typeof排除函数
最好
var properties = [
"first-name",
"last-name"
];
for (var i = 0; i < properties.length; i+=1){
document.writeln(properties[i] + ": " + stooge[properties[i]]);
}
删除
删除不会触及原型链，删除对象属性，原型链的属性浮现出来
anothet_stooge["first-name"] = "Jack";
document.writeln(anothet_stooge["first-name"]);//Jack
delete anothet_stooge["first-name"];
document.writeln(anothet_stooge["first-name"]);//Jerome
命名空间
var MYAPP= {}；
MYAPP.stooge = {
//...
};