JavaScript_原型链

function Fn(){ 
            this.test1 = function(){ 
                console.log('test1()'); 
            }; 
        } 
 
        Fn.prototype.test2 = function(){ 
            console.log('test2()'); 
        }; 
 
        var fn = new Fn(); 
 
        fn.test1();//"test1()" 
        fn.test2();//"test2()" 
        console.log(fn.toString());//"[object Object]" 
        fn.test3();//报错，"undefined is not a function"