JavaScript Learning Note 09 (constructors, prototypes,)

Prototype:

<script type= "Text/javascript" >
/**
* The following shows how prototypes are created, using prototype-based creation to set properties and methods
* is set to person-specific and can no longer be called by window
*/
function person () {

}
Person.prototype.name = "Leon";
Person.prototype.age = 23;
Person.prototype.say = function () {
Alert (this.name+ "," +this.age);
}
var p1 = new Person ();
P1.say ();
There is no way to invoke the say method through window, so the package is completed
Say ();
</script>

Four states of the prototype:

<script type= "Text/javascript" >
/**
* The prototype is a very special object in JS, and when a function is created, it produces a prototype object.
* When a specific object is created by the constructor of this function, in this specific object
* There will be a property pointing to the prototype
*/
The first state of
function person () {

}
Second State of
Person.prototype.name = "Leon";
Person.prototype.age = 23;
Person.prototype.say = function () {
Alert (this.name+ "," +this.age);
}
The third State, after an object has been created, will have a _prop_ attribute pointing to the prototype
If the property is not found inside the object when it is used, it will be found in the prototype, the _prop_ property is hidden
var p1 = new Person ();
P1.say ();
The following methods can be used to detect if the P1 has a _prop_ point to person's prototype
Alert (Person.prototype.isPrototypeOf (p1));

Fourth state of
var p2 = new Person ();
is to define an attribute in its own space that does not replace the property in the prototype
P2.name = "Ada";
P2.say ();
P1.say ();

Detects whether an object is a prototype of a function
Alert (Person.prototype.isPrototypeOf (p2));

Detecting the constructor of an object
alert (P1.constructor==person);

To detect whether a property is its own property
Alert (P1.hasownproperty ("name"));//false,p1 has no value in its own space
Alert (P2.hasownproperty ("name"));//true,p2 set the Name property in its own space

Delete P2.name;
P2.say ();
Alert (P2.hasownproperty ("name"));//Because it has been deleted, it is false

Detects whether an object contains a property in the prototype or itself, through in detection
Alert ("name" in p1);//true
Alert ("name" in P2);//true
Alert ("Address" in p1);//Not in prototype and in own space, false

Alert (Hasprototypeproperty (P1, "name"));//true
Alert (Hasprototypeproperty (P2, "name"));//false
/**
* You can detect whether a property exists in the prototype by the following methods
*/
function Hasprototypeproperty (obj,prop) {
Return ((!obj.hasownproperty (prop) && (prop in obj))
}
</script>

JavaScript Learning Note 09 (constructors, prototypes,)