编辑代码

//JSRUN引擎2.0，支持多达30种语言在线运行，全仿真在线交互输入输出。 
var Dog = function(firstname,lastname) {
  this.firstname = firstname
  this.lastname = lastname
}
Dog.prototype.bark = function() {
  console.log('wangwang')
}
Dog.prototype.sayName = function() {
  console.log('my name is ' + this.firstname + this.lastname)
}
// let chenjing = new Dog('chen','jing')
// chenjing.bark()
// chenjing.sayName()
function _new(fn,...args){
    let obj = Object.create(fn.prototype)
    ret = fn.apply(obj,args)
    return ret instanceof Object?ret:obj
}
let chenjing = _new(Dog,'chen','jing')
chenjing.bark()
chenjing.sayName()