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JavaScript

Posted by Daniel Sokol
Daniel Sokol
14,888 Points

Project file 'dice_finished' different than video

Hi there...

Is it me, or does the video have different code than the project files for the dice roll project?

The dice_finished project file shows the following:

function Dice(sides) {
  this.sides = sides;
}

Dice.prototype.roll = function () {
    var randomNumber = Math.floor(Math.random() * this.sides) + 1;
    return randomNumber;
}

var dice = new Dice(6);
var dice10 = new Dice(10);

console.log(dice.roll === dice10.roll);

Specifically, I'm confused about 'Dice.prototype.roll' and also using the keyword 'new' in the variables which is not discussed in the videos.

Thanks!

Steven Parker
Steven Parker
243,656 Points
Steven Parker
Steven Parker
243,656 Points

Which course and video are you referring to? Can you provide a link?

1 Answer

Steven Parker
Steven Parker
243,656 Points
Steven Parker
Steven Parker
243,656 Points

The "new" keyword constructs an object using the constructor function that follows it. It insures that references to "this" inside the constructor point to the object being created.

Using prototype to add new methods to a constructor function has two major benefits:

  1. the method becomes available to previously constructed instances of the object
  2. the method code is shared between the objects instead of each having its own copy

The sample code above appears to be designed to illustrate the second concept. The final line logs "true" to the console to show that both objects share the same method code.

sp:sparkles: