script.js

let celsius = document.getElementById('celsius');
let fahrenheit = document.getElementById('fahrenheit');
let kelvin = document.getElementById('kelvin');
celsius.oninput = () => {
  let output = (parseFloat(celsius.value) * 9) / 5 + 32;
  fahrenheit.value = parseFloat(output.toFixed(2));
  let k=(parseFloat(celsius.value)+273.15);
  kelvin.value=parseFloat(k.toFixed(2));
};

fahrenheit.oninput = () => {
  let output = ((parseFloat(fahrenheit.value) - 32) * 5) / 9;
  celsius.value = parseFloat(output.toFixed(2));
  let k=(parseFloat(fahrenheit.value)-32)*5/9+273.15;
  kelvin.value=parseFloat(k.toFixed(2));
};
kelvin.oninput = () => {
  let output = (parseFloat(kelvin.value) -273.15)*9/5+32;
  celsius.value = parseFloat(output.toFixed(2));
  let c=(parseFloat(kelvin.value)-273.15);
  kelvin.value=parseFloat(c.toFixed(2));
};