let interval = null; let result = null; function initJank() { const button = document.getElementById( 'button' ); button.addEventListener( 'click', function () { if ( interval === null ) { interval = setInterval( jank, 1000 / 60 ); button.textContent = 'STOP JANK'; } else { clearInterval( interval ); interval = null; button.textContent = 'START JANK'; result.textContent = ''; } } ); result = document.getElementById( 'result' ); } function jank() { let number = 0; for ( let i = 0; i < 10000000; i ++ ) { number += Math.random(); } result.textContent = number; } export default initJank;