app.js

let celsiusInput = document.querySelector("#celsius > input");
let fahrenheitInput = document.querySelector("#fahrenheit > input");
let kelvinInput = document.querySelector("#kelvin > input");
let btn = document.querySelector(".button button");

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

/*Celsius to fahrenheit and Kelvin*/

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

    fahrenheitInput.value = roundNumber(fTemp);
    kelvinInput.value = roundNumber(kTemp);
});

/* Fahrenheit to Celsius and Kelvin */

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

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

/* Kelvin to Celsius and Fahrenheit */

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

    celsiusInput.value = roundNumber(cTemp);
    fahrenheitInput.value = roundNumber(fTemp);
});


/* clear button */

btn.addEventListener("click", function(){
    celsiusInput.value = ""
    fahrenheitInput.value = ""
    kelvinInput.value = ""
})