base64direct.js

// On click, get base64 string, decode to ASCII, assume result is a url,
// send browser to url.
function go() {
    var b64box = document.getElementById("b64box");

    if (b64box.reportValidity() === true) {
        a = decode(b64box.value);
        location.assign(a.pop());
    }

    return false;
};


// On click, get base64 string, decode to ASCII, show intial string, all
// subsequent strings, and final, linkified ASCII result.
function show() {
    var b64box = document.getElementById("b64box");

    if (b64box.reportValidity() === true) {
        a = decode(b64box.value);

        showDiv = document.getElementById("showDiv");
        showDiv.innerHTML = "";
        for (let i=0; i<(a.length-1); i++) {
            showDiv.insertAdjacentHTML("beforeend", `<p>${a[i]}</p>`);
        }
        url = a.pop();
        showDiv.insertAdjacentHTML("beforeend", `<p><a href="${url}">${url}</a></p>`);
    }

    return false;
};

// Take a string, check if it's base64, decode if so, repeat until b64 check
// fails or 9 attempts, return an array of all decodings.
function decode(str) {
    const a = [];
    for (let i=0; i<9; i++) {
        a.push(str);
        try {
            window.atob(str);
        } catch (e) {
            return(a);
        }
        str = decodeURIComponent(escape(window.atob(str)));
        console.log(a[i]);
    }
    console.log("Error: Too many (10+) base64 decodings.")
    return(a);
};