index.js

generateDataSet() {
  this.updatedCells = [];
  ...
}

setPoint(point, state) {
  ...
  this.updatedCells.push(point);
}

render() {
  for (let i = 0; i < this.updatedCells.length; i++) {
    const point = this.updatedCells[i];
    ...
  }
  this.updatedCells = [];
}