1.

function People (name){
  this.name = name;
}

People.prototype.walk = function(){
  console.log(this.name + ' is walking');  
}

var p1 = new People('饥人谷');
var p2 = new People('前端');

原型图.jpg

2.

function People(){
}
var p = new People()
p.toString()

原型图2.jpg