const textEl = document.getElementById('text') const speedEl = document.getElementById('speed') const text = 'We Love Programming!' let idx = 1 let speed = 300 / speedEl.value writeText() function writeText() { textEl.innerText = text.slice(0, idx) idx++ if(idx > text.length) { idx = 1 } setTimeout(writeText, speed) } speedEl.addEventListener('input', (e) => speed = 300 / e.target.value)