Ajax无法弄清楚。

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                    <p class="mb0 mt6">Closed <span title="2014-08-08 12:44:21Z" class="relativetime">5 years ago</span>.</p>
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I just finished learning Ajax so I tried to make a simple project(a simple port scanner), it not working for me. I have no idea what is the problem. It's just showing 'Scan started'. please help me. There is no problem inside the php file, only in this code(VVVV)

var ports = [80, 22, 443, 21, 8080, 25, 3306];
function loadData(url, port){

    var xmlhttp;
    if (window.XMLHttpRequest)
    {// code for IE7+, Firefox, Chrome, Opera, Safari
    xmlhttp = new XMLHttpRequest();
    }
    else
    {// code for IE6, IE5
    xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
    }

    xmlhttp.onreadystatechange=function()
    {
    if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
        document.getElementById("myDiv").innerHTML += "<br>" + xmlhttp.responseText;
        }
    }

    xmlhttp.open("GET","scan.php?url=" + url + "&port=" + port,true);
    xmlhttp.send();

}

function scan () {
    // body...
    document.getElementById("myDiv").innerHTML = "Scan Started";
    if(document.getElementById("url").innerHTML){
        var url = document.getElementById("url").innerHTML;
        for (var i = 0; i < ports.length; i++) {
            loadData(url, ports[i]);
        };
    }
}
</script>
<center>
    <input type="text" id="url" name="url"><br><button onclick="scan()">Scan</button>
    <br>
    <div id="myDiv"></div>

Thanks, Mr. Frost

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Answer 1

To read the value from an text input, use the value property, not the innerHTML property.

An input element is defined as being EMPTY, it can't have any child nodes, so innerHTML should always be an empty string.