1.Object.create() 是什么？
Object.create(proto [, propertiesObject ]) 是E5中提出的一种新的对象创建方式，第一个参数是要继承的原型，如果不是一个子函数，可以传一个null，第二个参数是对象的属性描述符，这个参数是可选的。
例如：
function Car (desc) {
this.desc = desc;
this.color = "red";
}
Car.prototype = {
getInfo: function() {
return 'A ' + this.color + ' ' + this.desc + '.';
}
};
//instantiate object using the constructor function
var car = Object.create(Car.prototype);
car.color = "blue";
alert(car.getInfo());
结果为:A blue undefined.
2.propertiesObject 参数的详细解释：（默认都为false）
数据属性
- writable:是否可任意写
- configurable：是否能够删除，是否能够被修改
- enumerable：是否能用 for in 枚举
- value：值
访问属性：
- get(): 访问
- set(): 设置
3.例子：直接看例子就知道怎么用。
<!DOCTYPE html>
<html>
<head>
<title>yupeng's document </title>
<meta charset="utf-8"/>
</head>
<body>
<script type="text/javascript">
var obj = {
a:function(){
console.log(100)
},
b:function(){
console.log(200)
},
c:function(){
console.log(300)
}
}
var newObj = {};
newObj = Object.create(obj,{
t1:{
value:'yupeng',
writable:true
},
bar: {
configurable: false,
get: function() { return bar; },
set: function(value) { bar=value }
}
})
console.log(newObj.a());
console.log(newObj.t1);
newObj.t1='yupeng1'
console.log(newObj.t1);
newObj.bar=201;
console.log(newObj.bar)
function Parent() { }
var parent = new Parent();
var child = Object.create(parent, {
dataDescriptor: {
value: "This property uses this string as its value.",
writable: true,
enumerable: true
},
accessorDescriptor: {
get: function () { return "I am returning: " + accessorDescriptor; },
set: function (val) { accessorDescriptor = val; },
configurable: true
}
});
child.accessorDescriptor = 'YUPENG';
console.log(child.accessorDescriptor);
var Car2 = function(){
this.name = 'aaaaaa'
} //this is an empty object, like {}
Car2.prototype = {
getInfo: function() {
return 'A ' + this.color + ' ' + this.desc + '.';
}
};
var newCar = new Car2();
var car2 = Object.create(newCar, {
//value properties
color: { writable: true, configurable:true, value: 'red' },
//concrete desc value
rawDesc: { writable: true, configurable:true, value: 'Porsche boxter' },
// data properties (assigned using getters and setters)
desc: {
configurable:true,
get: function () { return this.rawDesc.toUpperCase(); },
set: function (value) { this.rawDesc = value.toLowerCase(); }
}
});
car2.color = 'blue';
console.log(car2.getInfo());
car2.desc = "XXXXXXXX";
console.log(car2.getInfo());
console.log(car2.name);
</script>
</body>
</html>
结果为：