CODEWITHSUNDEEP
javascript
user7103883
user7103883

Reputation: 87

Why fn. isn't a fn. (prototypes)?

Console said

Uncaught TypeError: Game.start is not a function.

JS:

window.onload = function () {

let socket = io();

function Game() {
    let self = this;
}

Game.prototype.start = function () {
    alert("something");
}

socket.on("ready", function (data) {
    Game.start();
    console.log("this console.log is work");
});
}

What is wrong?

Upvotes: 0

Views: 44

Answers (2)

Niels Steenbeek
Niels Steenbeek

Reputation: 4834

Keep scope by using => instead of function.

socket.on("ready", data => {
    Game.start();
    console.log("this console.log is work");
});

Upvotes: 0

Jonas Wilms
Jonas Wilms

Reputation: 138457

Game.prototype.start()

or

(new Game()).start();

Some explanations: Game will look like this:

Game={
 prototype:{
   start:function(){}
 }
 }

So Game.start() wont work as theres no start in Game. If you do new Game it creates an instance that inherits from Game.prototype. Therefore you can call start on that instance. If you wanna call some other functions on that game instance you might store it in a variable

mygameinstance = new Game;
mygameinstance.start();
mygameinstance.dosomeweirdstuff();

I think you havent had a deeper look into inheritance ...

Upvotes: 1

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