js对象构造方法

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1. 第一种
   var Car = function() {
   this.wheels = 4;
   this.engines = 1;
   this.seats = 1;
   };
2. 第二种
   var Car = function(wheels, seats, engines) {
   this.wheels = wheels;
   this.seats = seats;
   this.engines = engines;
   };
3. 第三种
   var car = {
   “wheels”:4,
   “engines”:1,
   “seats”:5
   };