dongluan7821 2014-12-29 18:04
浏览 45

xmlhttp.readyState没有改变

i was trying to build a application that demonstrate the use of ajax. as i am a newbie in ajax i couldnt able to find the error for my code. xmlhttp object is creating, rest of the things are not working, the ready state is not changing to 1 or more than that, i have tried by printing all status values.

<html>
<head>
<title>Home</title>
<script type="text/JavaScript"> 

 function process()
 {
  var xmlhttp;
    if (window.XMLHttpRequest)
    {

        xmlhttp=new XMLHttpRequest();
    }
    else
    {
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }

  if (xmlhttp.readyState==4 && xmlhttp.readyState==0)
    {
        food= document.getElementById("username").value;
        xmlhttp.open("GET","food.php?food="+food,true);
        xmlhttp.onreadystatechange=handleServerResponse();
        xmlhttp.send();     
    }
    else
    {
        setTimeout("process()",1000);
    }
}

response function,

function handleServerResponse()
{
    if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {   
                        xmlResponse=xmlhttp.ResponseXML;

                        xmlDocumentElement= xmlResponse.documentElement;

                        message=xmlDocumentElement.firstChild.data;

                        document.getElementById("status").innerHTML="message";

            setTimeout("process()",1000);

        }
}

</script>
</head>

<body >
<form  method="post">
<fieldset><center><h2>Login</h2></center>
    <label>Username</label>
        <input type="text" id="username"  value="" maxlength="20" /> 
    <div id="status" ></div>
        <input type="button" value=" Login " onClick="process()" />
</fieldset>
</form>
</body>
</html>

php code is below 

<?php
echo "<?xml version='1.0' encoding='UTF-8' standalone='yes'?>";
echo "<response";
$food=$_GET['food'];
if($food=="ajith")
  echo "Successs";
else
   echo "Invalid";
echo "</response>";   


?>
  • 写回答

1条回答 默认 最新

  • duanjieyi6582 2014-12-29 18:06
    关注

    var is not optional, use it.

    First var xmlhttp; is a local variable, so you would not be able to use it in the other method. Needs to be moved outside of the process function.

    Your if check is is impossible 

    xmlhttp.readyState==4 && xmlhttp.readyState==0

    How can something be 2 values at once?

    xmlhttp.readyState==4 || xmlhttp.readyState==0

    Next issue is the fact you are not assigning an event handler you are calling it

    xmlhttp.onreadystatechange=handleServerResponse();

    needs to be

    xmlhttp.onreadystatechange=handleServerResponse;

    There is no ResponseXML, there is responseXML

    "message" is a string, not the variable you defined beforehand.

    var xmlhttp;
function process () {
    if (window.XMLHttpRequest) {
        xmlhttp=new XMLHttpRequest();
    } else {
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }

    if (xmlhttp) {
        var food= document.getElementById("username").value;
        xmlhttp.open("GET","food.php?food="+food,true);
        xmlhttp.onreadystatechange=handleServerResponse;
        xmlhttp.send();     
    } else {
        //alert("Can not make Ajax request");
    }
}

function handleServerResponse () {
    if (xmlhttp.readyState==4 && xmlhttp.status==200) {   
        var xmlResponse=xmlhttp.responseXML;
        var xmlDocumentElement= xmlResponse.documentElement;
        var message=xmlDocumentElement.firstChild.data;
        document.getElementById("status").innerHTML = message;
        window.setTimeout(process,1000);
    }
}
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