What am I doing wrong here?

Question

<!DOCTYPE html>
<html lang="en">
  <head>
    <title> JavaScript Foundations: Objects</title>
    <style>
      html {
        background: #FAFAFA;
        font-family: sans-serif;
      }
    </style>
  </head>
  <body>
    <h1>JavaScript Foundations</h1>
    <h2>Objects: Prototypes</h2>
    <script>


      var carPrototype = {
        model: "generic",
        currentGear: 0,
        increaseGear: function() {
          this.currentGear ++;
        },
        decreaseGear: function() {
          this.currentGear--;
        } 
      }

      function Car(kind) {
          Car.model = kind;
      }


    </script>
  </body>
</html>

Answer 1 · 2014-05-04T20:33:05Z

May 4, 2014 8:33pm

Try this:

function Car(kind) {
    this.model = kind;
    this.currentGear = 1;
    return this;
}

Car.prototype.increaseGear = function() {
    this.currentGear++;
} 

Car.prototype.decreaseGear = function() {
    this.currentGear--;
} 

var jaguar = new Car("jaguar");
console.log(jaguar);
jaguar.increaseGear();
jaguar.increaseGear();
console.log(jaguar);
var bmw = new Car("bmw");
bmw.decreaseGear();  // unfortunately this will probably break the car
console.log(bmw);

In general, use prototype to add functions and properties that will be shared by every instance of the object. In this case, each car will have its own model and currentGear, so that can go in the original constructor. However, every car instance will share the same increaseGear and decreaseGear functions so they should go in the prototype.

Answer 2 · 2014-05-03T20:29:10Z

May 3, 2014 8:29pm

function Car(kind) {
   Car.model = kind;
}


      Car.prototype = {
        model: "generic",
        currentGear: 0,
        increaseGear: function() {
          this.currentGear ++;
        },
        decreaseGear: function() {
          this.currentGear--;
        } 
      }

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What am I doing wrong here?

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