Javascript 如何在子类中定义getter和setter属性
我有以下继承代码:Javascript 如何在子类中定义getter和setter属性,javascript,prototype,Javascript,Prototype,我有以下继承代码: SubClass= function () { ParentClass.call(this); } SubClass.prototype = Object.create(ParentClass.prototype); SubClass.prototype.constructor = SubClass; 但是,我也想在子类中定义一些属性: SubClass.prototype = { get x() { return this.newX;
SubClass= function () {
ParentClass.call(this);
}
SubClass.prototype = Object.create(ParentClass.prototype);
SubClass.prototype.constructor = SubClass;
但是,我也想在子类中定义一些属性:
SubClass.prototype = {
get x() {
return this.newX;
},
set x(val) {
this.newX = val;
alert("X has a value of " + this.newX);
}
}
我面临的问题是将两者结合起来。换句话说,在第一个代码示例中,我要说:
SubClass.prototype = Object.create(ParentClass.prototype);
SubClass.prototype = {...
但在第二个代码示例中,我要说:
SubClass.prototype = Object.create(ParentClass.prototype);
SubClass.prototype = {...
我怎样才能做到两者?允许我从父类继承并使用相同的原型定义定义属性的语法是什么
谢谢:)通过向
对象传递属性描述符来定义属性。defineProperty
:
Object.defineProperty(SubClass.prototype, 'x', {
configurable: true,
get: function () {
return this.newX;
},
set: function (val) {
this.newX = val;
alert("X has a value of " + this.newX);
},
});
还可以将包含属性描述符的对象传递给对象。创建:
function SubClass() {
ParentClass.call(this);
}
SubClass.prototype = Object.create(ParentClass.prototype, {
constructor: {
configurable: true,
writable: true,
value: SubClass,
},
x: {
configurable: true,
get: function () {
return this.newX;
},
set: function (val) {
this.newX = val;
alert("X has a value of " + this.newX);
},
}
});
如果您可以使用ES6类,它们会更好:
class SubClass extends ParentClass {
get x() {
return this.newX;
}
set x(val) {
this.newX = val;
alert("X has a value of " + this.newX);
}
}
您还可以制作这种有用的功能:
function extend(target, source) {
Object.getOwnPropertyNames(source).forEach(function (name) {
var descriptor = Object.getOwnPropertyDescriptor(source, name);
Object.defineProperty(target, name, descriptor);
});
}
并像这样使用它:
extend(SubClass.prototype, {
get x() {
return this.newX;
},
set x(val) {
this.newX = val;
alert("X has a value of " + this.newX);
},
});