???? JS ?????? ????? ??? ??? ?????, JS ?????? ????? ??? ??? ? ????? ???? ????????. ??? ?? ?????.

??? ??? ?? ???? ????? ??? ????. ? ??? ????? ??? ???? ?????, ? ????? ??? ??? ???? ?? ?????? ??? ? ????.

function?Person(){
}
Person.prototype.name?=?"Nicholas";
Person.prototype.age?=?29;
Person.prototype.sayName?=?function(){
alert(this.name);
};
var?person1?=?new?Person();
person1.sayName();?//"Nicholas"
var?person2?=?new?Person();
person2.sayName();?//"Nicholas"
alert(person1.sayName?==?person2.sayName);?//true

1. ????? ?? ????

??? ??? ??? ??? ?? ?? ??? ?? ??? ?? ????? ??? ?????. ? ??? ??? ????? ??? ?????.

????? ?? ????? ??? ????? ??? ?? ??? ?? ???? ???? ??? ??? ???? ????.

? ????? ???? ?? ???? ???? ?????? ???? ????? ??? ???? ???(?? ??)? ?????. ECMA-262 ?? 5??? ? ???? [[Prototype]]??? ????.

?????? [[Prototype]]? ????? ?? ??? ??? Firefox, Safari ? Chrome? ?? ???? ?? ??? __proto__ ??? ????? ? ??? ????? ?? ???? ????.

??? ??? ?? ? ?? ??? ?? ? ??? ????? ??? ??? ??? ????? ???? ????? ?? ??? ????? ????.

????? ???? ?? Person ???? Person.prototype? ???? ?? ??? ?? ??, ?? 6-1? ? ?? ?? ??? ?????.

??? Person.prototype? ????? ??? ???? Person.prototype.constructor? Person? ?? ?????.

person1? person2 ?? Person.prototype? ???? ?? ??? ?????. ?, ???? ???? ??? ????.

person1.sayName() ?? ??? ? ????. ?? ?? ??? ?? ????? ?? ?????. (?? ????? ????, ?? ? ??? ?????? ?? ?????.)

用isPrototypeOf()方法判斷實(shí)例與原型對(duì)象之間的關(guān)系
alert(Person.prototype.isPrototypeOf(person1));?//true
alert(Person.prototype.isPrototypeOf(person2));?//true
用Object.getPrototypeOf()?方法返回實(shí)例的原型對(duì)象
alert(Object.getPrototypeOf(person1)?==?Person.prototype);?//true
使用?hasOwnProperty()?方法可以檢測(cè)一個(gè)屬性是存在于實(shí)例中，還是存在于原型中。
alert(person1.hasOwnProperty("name"));?//false　　來(lái)著原型
person1.name?=?"Greg";
alert(person1.name);?//"Greg"——來(lái)自實(shí)例
alert(person1.hasOwnProperty("name"));?//true

2. ? ??? ????? ??

?? ???? Person.prototype? ???? ???. ??? ???? ??? ???. ???? ??? ??? ?????? ??? ????? ? ? ????? ?? ?? ??? ???? ???? ?? ???? ?? ????? ??? ????? ?? ? ??????.

function?Person(){
}
Person.prototype?=?{
　　name?:?"Nicholas",
　　age?:?29,
　　job:?"Software?Engineer",
　　sayName?:?function?()?{
　　　　alert(this.name);
　　}
};

? ????? Person.prototype? ?? ???? ??? ? ??? ???? ??????. ? ?? ??? ???? ?? ??? ?????. ??? ??? ? ?? Person ? ???? ????.

?? ????? ??? ??? ??? ?? ????? ??? ??? ???? ? ??? ???? ??? ??? ????.

var?friend?=?new?Person();
alert(friend?instanceof?Object);?//true
alert(friend?instanceof?Person);?//true
alert(friend.constructor?==?Person);?//false
alert(friend.constructor?==?Object);?//true

??? object ? Person? ????? ?? instanceof ???? ???? ??? true? ????? ??? ??? Object? ?? Person?? ?? ????.

???? ?? ?? ??? ?? ??? ?? ????? ??? ??? ?? ??? ? ????.

function?Person(){
}
Person.prototype?=?{
??constructor?:?Person,
??name?:?"Nicholas",
??age?:?29,
??job:?"Software?Engineer",
??sayName?:?function?()?{
????alert(this.name);
??}
};

3. ???? ??? ?????

?? ???? ?? ??(Object, Array, String ?)?? ???? ?????? ??? ???? ????.

?? ?? sort() ???? Array.prototype?? ?? ? ?? substring() ???? String.prototype?? ?? ? ????. ?????? ???? ??? ?????? ???? ?? ???? ????.

4. ????? ??? ??

????? ??? ?? ? ??? ?? ???? ?????. ? ? ??? ???? ?? ???? ??? ????.

function?Person(){
}
Person.prototype?=?{
constructor:?Person,
name?:?"Nicholas",
age?:?29,
job?:?"Software?Engineer",
friends?:?["Shelby",?"Court"],
sayName?:?function?()?{
alert(this.name);
}
};
var?person1?=?new?Person();
var?person2?=?new?Person();
person1.friends.push("Van");
alert(person1.friends);?//"Shelby,Court,Van"
alert(person2.friends);?//"Shelby,Court,Van"
alert(person1.friends?===?person2.friends);?//true

5. ????? ??

?? ????? ?????? ???? ??? ?? ??? ?? ?? ??? ??? ???? ????? ?? ????. ?? ?? ????? ????? ?????? ??? ?????. ??? ?? ????? ??? ?? ?????.

function?SuperType(){
　　this.property?=?true;
}
SuperType.prototype.getSuperValue?=?function(){
　　return?this.property;
};
function?SubType(){
　　this.subproperty?=?false;
}
//繼承了?SuperType
SubType.prototype?=?new?SuperType();
SubType.prototype.getSubValue?=?function?(){
　　return?this.subproperty;
};
var?instance?=?new?SubType();
alert(instance.getSuperValue());?//true

　?? ??:

??? SubType.prototype? ????. ?? ??? ???? ???? getSuperValue()? ????? ????? ?????. SubType.prototype? ?? SuperType? ??????? ?? ??? ?? ????? ????.

? ??? ??? ?? ? ??? ?????? ?????. ? ???? ??? ??? PHP ??? ????? ?? ?? ??? ?????!

?? ??:

preload() ???

react+native+video? ??? ??? ???? ?? ?? ?? ???

? ??? JS ????? ? ????? ?? ?? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!