script.js

let celsiusInput = document.querySelector('#celsius > input')
let farenheitInput = document.querySelector('#farenheit > input')
let kelvinInput = document.querySelector('#kelvin > input')

function roundNumber(number) {
    return Math.round(number*100)/100
}

celsiusInput.addEventListener('input', function(){
    let cTemp = parseFloat(celsiusInput.value)
    let fTemp = (cTemp * (9 / 5)) + 32
    let kTemp = cTemp + 273.15

    farenheitInput.value = roundNumber(fTemp)
    kelvinInput.value = roundNumber(kTemp)
})

farenheitInput.addEventListener('input', function () {
    let fTemp = parseFloat(farenheitInput.value)
    let cTemp = (fTemp- 32)*(5/9)
    let kTemp = (fTemp - 32) * (5 / 9) + 273.15

    celsiusInput.value = roundNumber(cTemp)
    kelvinInput.value = roundNumber(kTemp)
})

kelvinInput.addEventListener('input', function () {
    let kTemp = parseFloat(kelvinInput.value)
    let fTemp = ((kTemp - 273.15) * (9 / 5)) + 32
    let cTemp = kTemp - 273.15

    farenheitInput.value = roundNumber(fTemp)
    celsiusInput.value = roundNumber(cTemp)
})