JS - setInterval

What is setInterval?

setInterval() method, offered on the Window and Worker interfaces, repeatedly calls a function or executes a code snippet, with a fixed time delay between each call.

let timerId = setTimeout(func|code, [delay], [arg1], [arg2], ...)

func|code

Function or a string of code to execute. Usually, that’s a function. For historical reasons, a string of code can be passed, but that’s not recommended.

delay

The delay before run, in milliseconds (1000 ms = 1 second), by default 0.

arg1, arg2…

Arguments for the function (not supported in IE9-)

In-Action 1

function sayHi(phrase, who) {
  alert( phrase + ', ' + who );
}

setTimeout(sayHi, 1000, "Hello", "John"); // Hello, John

In-Action 2

    <div class="clock">
      <div class="clock-face">
        <div class="hand hour-hand"></div>
        <div class="hand min-hand"></div>
        <div class="hand second-hand"></div>
      </div>
    </div>

  const secondHand = document.querySelector('.second-hand');
  const minsHand = document.querySelector('.min-hand');
  const hourHand = document.querySelector('.hour-hand');

  function setDate() {
    const now = new Date();

    const seconds = now.getSeconds();
    const secondsDegrees = ((seconds / 60) * 360) + 90;
    secondHand.style.transform = `rotate(${secondsDegrees}deg)`;

    const mins = now.getMinutes();
    const minsDegrees = ((mins / 60) * 360) + ((seconds/60)*6) + 90;
    minsHand.style.transform = `rotate(${minsDegrees}deg)`;

    const hour = now.getHours();
    const hourDegrees = ((hour / 12) * 360) + ((mins/60)*30) + 90;
    hourHand.style.transform = `rotate(${hourDegrees}deg)`;
  }

  setInterval(setDate, 1000);

  setDate();

REF

https://developer.mozilla.org/en-US/docs/Web/API/setInterval
https://javascript.info/settimeout-setinterval