var req;
function doSubmit() {
    var inputField = document.getElementById("input");
    var input = escape(inputField.value);
	input = input.replace(/\+/g, '%2B');
    input = input.replace(/%20/g, '+');
    var url="execute?input=" + input;
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
    } else if (window.ActiveXObject) {
        req = new ActiveXObject("Microsoft.XMLHTTP");
    }
    req.open("GET", url, true);
    req.onreadystatechange = callback;
    req.send(null);
    return false;
}
function callback() {
    if (req.readyState == 4 && req.status == 200) {
        parseMessage();
        clearInput();
    }
}

function parseMessage() {
    var message = req.responseText;
    setMessage(message);
}

function setMessage(message) {
    var outputElement = document.getElementById("output");
    var inputElement = document.getElementById("input");
    outputElement.innerHTML += "<span class='input'>" + inputElement.value + "</span>" + "<BR>" + "<span class='output'>" + message + "</span>";
    outputElement.scrollTop = outputElement.scrollHeight;
}

function clearInput() {
    var inputElement = document.getElementById("input");
    inputElement.value = "";
}