Javascript setInterval not working for object method [duplicate]

Question

I'm trying to run a 'Car' object method across the browser window with 'setInterval' but it only work once. What's the problem of my code? Also, I am confused if we put the function in setInterval with parenthesis or without it?

Here is my code:

var Car = function(x, y) {
  this.x = x;
  this.y = y;
  //   drawing in constructor
  this.draw();
};
Car.prototype.draw = function() {
  var carhtml =
    '<img src="https://www.pngitem.com/pimgs/m/195-1953962_vector-vintage-classic-car-free-hd-image-clipart.png">';

  this.carElement = $(carhtml);
  this.carElement.css({
    position: "absolute",
    left: this.x,
    top: this.y,
    width: 400,
  });
  $("body").append(this.carElement);
};
Car.prototype.moveRight = function() {
  this.x += 10;
  this.carElement.css({
    left: this.x,
    top: this.y,
  });
};
var classicCar = new Car(0, 100);
setInterval(classicCar.moveRight, 1000);

<script src="https://code.jquery.com/jquery-2.1.0.js"></script>

Hello there Hy Lai. Welcome to StackOverflow. Your code is working perfectly. The car Object simply moves off the right-hand side of the screen and keeps going! If this is not what you want please edit your question to explain exactly what you would like to happen. — Brian Peacock
– Brian Peacock, Commented Jan 3, 2022 at 9:39
@BrianPeacock The code gives error due to this not being what OP thinks it is — mplungjan
– mplungjan, Commented Jan 3, 2022 at 9:43

shidoro · Accepted Answer · 2022-01-03 09:44:15Z

2

You are losing the reference to the this variable. Bind it to the object

setInterval(classicCar.moveRight.bind(classicCar), 1000);

answered Jan 3, 2022 at 9:44

shidoro

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1 Comment

Hy Lai Over a year ago

Thanks this works! I will go and find out thebind functions.

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