Converting circular structure to JSON

const getCircularReplacer = () => {
  const seen = new WeakSet();
  return (key, value) => {
    if (typeof value === "object" && value !== null) {
      if (seen.has(value)) {
        return;
      }
      seen.add(value);
    }
    return value;
  };
};

JSON.stringify(circularReference, getCircularReplacer());
//The error means that the object you pass in the request has a circular reference, something like:

var a = {};
a.b = a;I also ran into this issue. It was because I forgot to await for a promise.Game.prototype.restart = function () {
  this.clearLocalStorage();
  this.timer = setTimeout(this.reset.bind(this), 0);  // bind to 'this'
};

Game.prototype.reset = function(){
    this.clearBoard();    // ahhh, back in the context of the right 'this'!
};