extend (继承)
如何用 es5 实现继承
Father.prototype = {
eat:function(){
console.log(this.name+' eat something.')
}
}
function Father(name) {
this.name = name
this.attr = "father's attr."
}
function Super() {
this.constructor = Child
}
Super.prototype = Father.prototype
Child.prototype = new Super() // 继承父类的原型方法
function Child() {
Father.apply(this, arguments) // 继承父类的属性
this.attr = "child's attr"
}
测试
var child = new Child('Foo')
console.log(child,child.attr)
console.log(child instanceof Child, child instanceof Father)
child.eat()
console.log(child.newAttr)
Father.prototype.newAttr = '123'
console.log(child.newAttr)
console.log(Child.prototype.constructor === Child)
结果
Child { name: 'Foo', attr: 'child\'s attr' } 'child\'s attr'
true true
Foo eat something.
undefined
123
true
