How does 'this' work in JavaScript?

Question

I know there are several other posts on this topic but they still leave me confused.

I\'ve included jQuery and everything and, I have a simple javascript class like

Answer 1

function CarConstructor(){
  var _this = this;  
  this.speed=19; // in mph
  this.make="Ford";
  this.fillKph = function (){
      $("#kphdiv").html(_this.speed*1.61);
  };
}

car1 = new CarConstructor();
car1.fillKph();