javascript prototype
Download as PPTX, PDF1 like604 views
This document discusses JavaScript prototypes and the prototype chain. It provides examples of how to set up prototype chains between functions to inherit and share properties and methods. It also demonstrates how the prototype property works and how to access properties and methods from different levels in the prototype chain.
![function test(){ Function['test'] = {
... ...
} prototype:{
alert( typeof test.prototype );
constructor:Function['test']
alert( test === test.prototype.constructor ); }
};
var a = new test( 3 ); var a = {
__proto__:test.prototype
alert( a.constructor === test ); };
alert( a instanceof test );
a = test.call( a, 3 ) || a;
function test( $val ){ a={
this.val = $val; __proto__:test.prototype,
}
val:3
};
function test( $val ){ a = {};
this.val = $val;
return {};
}](https://image.slidesharecdn.com/s532-121031004439-phpapp01/85/javascript-prototype-3-320.jpg)
![function parent(){ a={
} __proto__:child.prototype
parent.prototype.add = function(){}; };
function child(){ //1. a[???]
} //2. a.__proto__[???]
child.prototype.action = function(){};
a.add === undefined
var a = new child;
a.add();
Goal = a.__proto__.__proto__.add();
1. a.__proto__ = child.prototype;
2. a.__proto__.__proto__ = child.prototype.__proto__ = parent.prototype;
3. child.prototype = new parent;
4. a.__proto__.__proto__.add = parent.prototype.add;](https://image.slidesharecdn.com/s532-121031004439-phpapp01/85/javascript-prototype-5-320.jpg)
javascript prototype
- 1. S53 #2 2-1 type 2-2 prototype 2-3 prototype chain 2-4 technique 2012.10.24 20:30 ~ 22:30
- 2. Type = Id = Category = Group var a = {type:1}; int memory▼ recognize▼ scalable● var b = {type:2}; var a = {type:"food"}; String memory▲ recognize▲ scalable▼ var b = {type:"tool"}; Object memory▼ recognize▲ scalable▲ var food = {}; var tool = {}; Self(Recusive) - Reference var a = {type:food}; var food = {}; var b = {type:tool}; var tool = {}; alert( food.type ); Conclusion = Function var food = function(){}; var tool = function(){}; var a = {type:food}; var b = {type:tool}; alert( a.type ); // food alert( food.type ); // undefined
- 3. function test(){ Function['test'] = { ... ... } prototype:{ alert( typeof test.prototype ); constructor:Function['test'] alert( test === test.prototype.constructor ); } }; var a = new test( 3 ); var a = { __proto__:test.prototype alert( a.constructor === test ); }; alert( a instanceof test ); a = test.call( a, 3 ) || a; function test( $val ){ a={ this.val = $val; __proto__:test.prototype, } val:3 }; function test( $val ){ a = {}; this.val = $val; return {}; }
- 4. function test1(){ var a = new test1; } function test2(){ alert( a.constructor === test1 ); } alert( a instanceof test1 ); test1.prototype.constructor = test2; alert( test2 === test1.prototype.constructor ); test1.prototype = test2.prototype; function test(){ alert( test2 === test1.prototype.constructor ); } test.prototype.val = 3; function test(){ } var a = new test, b = new test; test.prototype.action = function(){}; alert( a.val ); var a = new test, b = new test; a.val = 5; alert( a.action === b.action ); alert( b.val );
- 5. function parent(){ a={ } __proto__:child.prototype parent.prototype.add = function(){}; }; function child(){ //1. a[???] } //2. a.__proto__[???] child.prototype.action = function(){}; a.add === undefined var a = new child; a.add(); Goal = a.__proto__.__proto__.add(); 1. a.__proto__ = child.prototype; 2. a.__proto__.__proto__ = child.prototype.__proto__ = parent.prototype; 3. child.prototype = new parent; 4. a.__proto__.__proto__.add = parent.prototype.add;
- 6. function parent(){ } parent.prototype.add = function(){}; parent.prototype.remove = function(){}; ... function child( a, b ){ this.a = a; this.b = b; } child.prototype = new parent; child.prototype.action1 = function(){}; child.prototype.action2 = function(){}; ... var a = new child; a.a; // a.a a.b; // a.b a.action1(); // a.__proto__.action1 a.action2(); // a.__proto__.action2 a.add(); // a.__proto__.__proto__.add a.remove(); // a.__proto__.__proto__.remove
- 7. function test( a, b ){ function test( a, b ){ if( this == window ){ ... return new test( a, b ); } }else{ this.a = a; test.prototype.action1 = function(){}; this.b = b; test.prototype.action2 = function(){}; } } test.prototype = { constructor: test.prototype.constructor, var a = test( 3, 5 ); action1: function(){}, var b = new test( 3, 5 ); action2: function(){} }; alert( a.constructor === b.constructor ); function parent( a ){ this.a = a; } function child( a, b ){ this.super( a ); this.b = b; } child.prototype = new parent; child.prototype.super = parent; var a = new child( 3, 6 ); alert( a.a );