下列代码的执行结果
function Fn1(name) {
 if(name){
  this.name = name;
 }
}
Fn1.prototype.name="jack"
let a = new Fn1();
console.log('a:', a.name);

function Fn2(name) {
 this.name = name;
}
Fn2.prototype.name="jack"
let b = new Fn2();
console.log('b:', b.name);