popup.js

function converter(numero) {
    var request = new XMLHttpRequest();
    request.open("GET", "https://api.coingecko.com/api/v3/simple/price?ids=lbry-credits&vs_currencies=usd");
    request.send();
    request.onload = () => {
        if (request.status == 200) {
            var response = JSON.parse(request.responseText);
        }
    }

    request.onload = () => {
        if (request.status == 200) {
            var response = JSON.parse(request.responseText);
            var result_tofix = response['lbry-credits'].usd * numero
            document.querySelector('#result').textContent = result_tofix.toFixed(4) + " USD";

        }
    }
}

document.addEventListener("DOMContentLoaded", function() {

    document.querySelector('#btn').addEventListener('click', function() {

        let numero = document.querySelector('#numero').value;

        converter(numero);
    })
})