javascript中的继承-优快云博客

本文详细解析了基于临时函数的继承机制，通过代码示例和对象关系图，深入探讨了JavaScript中如何实现类的继承。从基本概念到具体应用，全面展示了这一独特继承方式的实现原理和实践价值。

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摘自Object Oriented Javascript 一书

基于临时函数的继承机制

先上代码：

/* Temporary constructor */


function Shape() { }
Shape.prototype.name = 'Shape';
Shape.prototype.toString = function() {
    return this.name;
};

function Shape2D() { }
function A() { }
A.prototype = Shape.prototype;
Shape2D.prototype = new A();
Shape2D.prototype.constructor = Shape2D;
Shape2D.prototype.name = 'Shape 2D';

function Triangle(side, height) {
    this.side = side;
    this.height = height;
}
function B() { }
B.prototype = Shape2D.prototype;
Triangle.prototype = new B();
Triangle.prototype.constructor = Triangle;
Triangle.prototype.name = 'Triangle';
Triangle.prototype.getArea = function() {
    return this.side * this.height / 2;
}

// test
var t = new Triangle(10, 10);
console.log(t.getArea());
console.log(t.toString());      // 输出 Triangle

var s = new Shape();
console.log(s.toString());      // 输出 Shape

var s2d = new Shape2D();
console.log(s2d.toString());    // 输出 Shape 2D

再上对象关系图：