CODE EXAMPLE FOR JAVASCRIPT

interval in javascript

// variable to store our intervalID
let nIntervId;

function changeColor() {
  // check if already an interval has been set up
  if (!nIntervId) {
    nIntervId = setInterval(flashText, 5);
  }
}

function flashText() {
  const oElem = document.getElementById("my_box");
  if (oElem.className === "go") {
    oElem.className = "stop";
  } else {
    oElem.className = "go";
  }
}

function stopTextColor() {
  clearInterval(nIntervId);
  // release our intervalID from the variable
  nIntervId = null;
}

document.getElementById("start").addEventListener("click", changeColor);
document.getElementById("stop").addEventListener("click", stopTextColor);