1.constructor prototype详解 原型陷阱

funciton Dog(){

this.tail = true;

}

var benji  = new Dog();

var rusty = new Dog();

Dog.prototype.say  = function(){

return ' Woof ! ';

}

>>>benji,say();          constructor->Dog()

""Woof !"

var instead = {paws: 4,hair:true};       constructor->Object()

>>>Dog.prototype =instead;          constructor ->Object()

>>>benji.paws      constructor->Dog()

"undefined"

>>>benji.say()      constructor->Dog()

"Woof!"

var lucy = new Dog();         constructor->Object()

>>>lucy.say()

"TypeError:lucy.say is not a function"

>>>lucy.paws

4

解决办法：

Dog.prototype = {paws: 4, hair: true};

Dog.prototype.constructor = Dog;