Exercise 10 Part 1

Modern JavaScript Using Objects
6 minutes
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Transcript

For objects, we will have a single exercise however, we're going to divide that exercise into three parts. Basically, because the exercise consists of the same task, but doing it different ways, if you choose to, it is only necessary for you to watch the first part. unless you'd like to see additional ways of doing this exercise. Let me introduce what this Iman is. So this assignment would be the type of thing that you might do if you're creating a game in JavaScript. So what I'd like you to do is set up the creation of an object that uses a prototype.

And you can use either object create a constructor function, or the class definition. Now in part one, I'll show you object create part to the constructor and in part three, class. Now the purpose of the object is going to be a character for the game. So you need to set up a prototype to have the following properties, speed, strength and hit points and it gives you a default value for those. And then you also need to establish a method within the prototype and the method determines damage per second and returns it. And that's simply equal to the speed times the strength.

Once you've got that set up, create one object providing the values for speed and hit points don't provide a value for strength. We want that to use the value that's in the prototype. then display the damage per second. So in part one, you're going to use object create, you'll create an object first that will be the the prototype, and then you'll use object create to create your sample object here and you'll include in the print sees the object you set up as the prototype. Then you'll establish the values you want for speed and hit points, and then just console log the results of the damage per second when you call that method. Part Two, of course, you'll set up a constructor function.

And that constructor will need to check to see if it has a value passed in for speed, strength and hit points. If it does, it will use it. If it doesn't, it won't assign a value to that. That will ensure that it uses the prototype. Then you'll need to add to the prototype at default speed a default strain to default hit points and then the damage per second function. Now in the class definition, I want you to accomplish the same thing, but use a class instead.

Alright, so let's go ahead and pause the movie and when you're ready to To begin and view the method for doing an object create restart the movie. To view it for constructor function, you can view Part Two for the class definition, part three. All right, we're going to use object create to solve this problem. So first I need to set up I need to create an object that I'm going to use as the prototype in my object dot create statement. So I'm going to call it game character. And we're going to use the object literal to set that up.

So speed will be six that's the default that we're we are to establish for that strength will be eight and hit points. Oops, will be 150. Those are my defaults. Now I need to establish the method the damage per second. So I'm just going to call it damage per sec. And this will be a function and then function simply going to return this dot speed times this dot string.

That will return the damage per second. Okay, so we have that set up, we can now use that as the prototype that we pass in with object create. So I'm going to say create a sample character. And I'm going to set that equal to object create. And then in parentheses, I'm going to pass in my game character object that will create the object with all those defaults, but I want to override Ride or in want to not use the defaults for speed and hit points. So I set character one speed equal to nine and char one hit points equal to 205.

Now let's just see what the results are when we do console dot log, and then we call the char one damage per second method. And that will allow us to see what we get. So I'm going to save that. copy the file path. And let's see what we get. Open the console.

And 72 is the damage per second and that should be correct. Because I used we look at that. I use the nine as a speed we kept the default strength of eight. And so the fact that we get a number shows it's it's grabbing that from The prototype, and it's multiplying them to get 72. So that seems to be working correctly. So that's how we'll be done with object create.

Continue to part two, if you'd like to see how it's done with a constructor

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