JSFiddle - React, Tailwind, and code Playground

JavaScript

let firstTime = true;
let storedCount = 0;

const Component = () => {
  let count = storedCount;
  
  if (firstTime) {
    setInterval(() => {
      console.log(storedCount)
  	  storedCount = count + 1;
    }, 1000);
    firstTime = false;
  }
}

Component();
Component();
Component();

// prints incremented closed variable as expected
// closedVariable is correctly updated