Can I execute a function after setState is finished updating?

Question

I am very new to ReactJS (as in, just started today). I don\'t quite understand how setState works. I am combining React and Easel JS to draw a grid based on

Answer 1

With hooks in React 16.8 onward, it's easy to do this with useEffect

I've created a CodeSandbox to demonstrate this.

useEffect(() => {
  // code to be run when state variables in
  // dependency array changes
}, [stateVariables, thatShould, triggerChange])

Basically, useEffect synchronises with state changes and this can be used to render the canvas

import React, { useState, useEffect, useRef } from "react";
import { Stage, Shape } from "@createjs/easeljs";
import "./styles.css";

export default function App() {
  const [rows, setRows] = useState(10);
  const [columns, setColumns] = useState(10);
  let stage = useRef()

  useEffect(() => {
    stage.current = new Stage("canvas");
    var rectangles = [];
    var rectangle;
    //Rows
    for (var x = 0; x < rows; x++) {
      // Columns
      for (var y = 0; y < columns; y++) {
        var color = "Green";
        rectangle = new Shape();
        rectangle.graphics.beginFill(color);
        rectangle.graphics.drawRect(0, 0, 32, 44);
        rectangle.x = y * 33;
        rectangle.y = x * 45;

        stage.current.addChild(rectangle);

        var id = rectangle.x + "_" + rectangle.y;
        rectangles[id] = rectangle;
      }
    }
    stage.current.update();
  }, [rows, columns]);

  return (
    

      

        
        
Rows: {rows}
        
Columns: {columns}
      
      

        

          Number of Rows
           setRows(e.target.value)}
          >
            {getOptions()}
          
          Number of Columns
           setColumns(e.target.value)}
          >
            {getOptions()}
          
        
      
    
  );
}

const getOptions = () => {
  const options = [1, 2, 5, 10, 12, 15, 20];
  return (
    <>
      {options.map((option) => (
        
          {option}
        
      ))}
    
  );
};