JavaScript继承
JavaScript继承
提问于 2011-09-20 22:26:46
我正在尝试在javascript中实现继承。我想出了以下最少的代码来支持它。
function Base(){
this.call = function(handler, args){
handler.call(this, args);
}
}
Base.extend = function(child, parent){
parent.apply(child);
child.base = new parent;
child.base.child = child;
}专家们，请让我知道这是否足够或我可能遗漏的任何其他重要问题。根据面临的类似问题，请提出其他修改建议。
下面是完整的测试脚本：
function Base(){
this.call = function(handler, args){
handler.call(this, args);
}
this.superalert = function(){
alert('tst');
}
}
Base.extend = function(child, parent){
parent.apply(child);
child.base = new parent;
child.base.child = child;
}
function Child(){
Base.extend(this, Base);
this.width = 20;
this.height = 15;
this.a = ['s',''];
this.alert = function(){
alert(this.a.length);
alert(this.height);
}
}
function Child1(){
Base.extend(this, Child);
this.depth = 'depth';
this.height = 'h';
this.alert = function(){
alert(this.height); // display current object height
alert(this.a.length); // display parents array length
this.call(this.base.alert);
// explicit call to parent alert with current objects value
this.call(this.base.superalert);
// explicit call to grandparent, parent does not have method
this.base.alert(); // call parent without overriding values
}
}
var v = new Child1();
v.alert();
alert(v.height);
alert(v.depth);回答 12
Stack Overflow用户
发布于 2012-10-10 18:13:38
要在ECMAScript 5中实现javascript继承，您可以定义对象的原型并使用Object.create进行继承。您还可以根据需要添加/覆盖属性。
示例：
/**
* Transform base class
*/
function Transform() {
this.type = "2d";
}
Transform.prototype.toString = function() {
return "Transform";
}
/**
* Translation class.
*/
function Translation(x, y) {
// Parent constructor
Transform.call(this);
// Public properties
this.x = x;
this.y = y;
}
// Inheritance
Translation.prototype = Object.create(Transform.prototype);
// Override
Translation.prototype.toString = function() {
return Transform.prototype.toString() + this.type + " Translation " + this.x + ":" + this.y;
}
/**
* Rotation class.
*/
function Rotation(angle) {
// Parent constructor
Transform.call(this);
// Public properties
this.angle = angle;
}
// Inheritance
Rotation.prototype = Object.create(Transform.prototype);
// Override
Rotation.prototype.toString = function() {
return Transform.prototype.toString() + this.type + " Rotation " + this.angle;
}
// Tests
translation = new Translation(10, 15);
console.log(translation instanceof Transform); // true
console.log(translation instanceof Translation); // true
console.log(translation instanceof Rotation); // false
console.log(translation.toString()) // Transform2d Translation 10:15Stack Overflow用户
发布于 2012-04-20 19:59:59
我认为Crockfords的解决方案太复杂了，就像John的一样，获得javascript继承要比他们两个看起来都描述的简单得多。考虑一下：
//Classes
function A() {
B.call(this);
}
function B() {
C.call(this);
this.bbb = function() {
console.log("i was inherited from b!");
}
}
function C() {
D.call(this);
}
function D() {
E.call(this);
}
function E() {
//instance property
this.id = Math.random()
}
//set up the inheritance chain (order matters)
D.prototype = new E();
C.prototype = new D();
B.prototype = new C();
A.prototype = new B();
//Add custom functions to each
A.prototype.foo = function() {
console.log("a");
};
B.prototype.bar = function() {
console.log("b");
};
C.prototype.baz = function() {
console.log("c");
};
D.prototype.wee = function() {
console.log("d");
};
E.prototype.woo = function() {
console.log("e");
};
//Some tests
a = new A();
a.foo();
a.bar();
a.baz();
a.wee();
a.woo();
console.log(a.id);
a.bbb();
console.log(a instanceof A);
console.log(a instanceof B);
console.log(a instanceof C);
console.log(a instanceof D);
console.log(a instanceof E);
var b = new B();
console.log(b.id)我已经在my blog上编写了上述解决方案的完整描述。
Stack Overflow用户
发布于 2013-02-04 04:42:08
当我使用JS对象时，我发现了一个更简约的解决方案:-)享受！
function extend(b,a,t,p) { b.prototype = a; a.apply(t,p); }示例
function A() {
this.info1 = function() {
alert("A");
}
}
function B(p1,p2) {
extend(B,A,this);
this.info2 = function() {
alert("B"+p1+p2);
}
}
function C(p) {
extend(C,B,this,["1","2"]);
this.info3 = function() {
alert("C"+p);
}
}
var c = new C("c");
c.info1(); // A
c.info2(); // B12
c.info3(); // Cc页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/7486825
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