Uncaught SyntaxError: Unexpected token 'class'

Question

I'm trying to make a class GameState with a constructor function to assign my variables. I keep getting the error: Uncaught SyntaxError: Unexpected token 'class' - but all of the documentation I can find says to do it this way. I'm not sure what's wrong. MDN Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/constructor

I also found this solution on stack overflow which also looks like what I have, but I'm still getting an error. ES6 Classes: Unexpected token in script?

I tried commenting out all of my code and pasting an example from MDN and it is throwing the same error https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/class

Could someone please help me out? I'm pretty new to programming but all of the documentation looks right, I'm still lost. Code below for reference.

class GameState {
    constructor() {
        this.board = [null, null, null, null, null, null, null, null, null];
        this.whoseTurn = 1;
        this.winner = null;
    }
}

let gs = new GameState();

See the [Browser Compatibility](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes#browser_compatibility) table — Barmar, Jul 01 '21 at 21:01
If you are using Internet Explorer, it's no wonder you get the error … — TheEagle, Jul 01 '21 at 21:11

ErrorGamer2000 · Accepted Answer · 2021-07-01T21:50:50.710

Firstly check the syntax before the class statement as @VLAZ said and put a semicolon if there is not one. Missing semicolons can cause strange errors.

The class statement is a feature new in ES2015. If you are using an older browser (eg. Internet Explorer) this will not work. Instead try a constructor function:

function GameState() {
  if (!(this instanceof GameState)) { //Function was called without the "new" keyword, so we return an instance instead of creating one.
    return new GameState();
  }
  this.board = [null, null, null, null, null, null, null, null, null];
  this.whoseTurn = 1;
  this.winner = null;
}
  
  

let gs = new GameState();

console.log(gs);

You can add prototype functions with GameState.prototype

function GameState() {
  if (!(this instanceof GameState)) { //Function was called without the "new" keyword, so we return an instance instead of creating one.
    return new GameState();
  }
  this.board = [null, null, null, null, null, null, null, null, null];
  this.whoseTurn = 1;
  this.winner = null;
}
  
GameState.prototype.getBoard = function () {
  return this.board;
};

let gs = new GameState();

console.log(gs.getBoard());

Hey guys, I have the same error right now, but in my case class is literally at the very first start of the script.. — Alex Ruhl, Sep 15 '21 at 16:49

Uncaught SyntaxError: Unexpected token 'class'

1 Answers1