An infinite loop in Javascript is a piece of code which executes indefinitely until the program is terminated.

Standard infinite loop using while

while(true) {

This program will print into the console Hello!Hello!Hello!Hello! indefinitely. 

Infinite loop with delay

The easiest way to create a javascript infinite loop with delay is to use the setInterval method. Here is an example of an infinite loop with setInterval.

let helloCounter = 1;
setInterval(() => {
  console.log(`Hello for the ${helloCounter} time`);
}, 5000);

This program will print Hello for the N time every 5 seconds indefinitely.

Why would you need an infinite loop?

Let's say you want a button that changes its color every 5 seconds. For this, you'll need a method which executes every 5 seconds indefinitely. Let's look at the example below.

<!DOCTYPE html>
  <title>Color Changing Button</title>
  <button id="mybtn">Color changing button</button>

    const co = ['red', 'green', 'blue', 'black', 'yellow'];
    let colorIndex = 0;

    setInterval(() => {
      document.getElementById("mybtn").style.backgroundColor = co[colorIndex];
      colorIndex = (colorIndex + 1) % co.length;
    }, 5000);

You can check this example at codepen.

Additional resources