你能告诉为什么javascript函数没有在profile.php的提交按钮中执行

Here is the code for profile.php in , in the submit button the onclick event doesnt working tell me where the mistakes are there the javascript function doesnt loading at all

<?php include("./inc/header.inc.php"); ?>
<?php include("./inc/connect.inc.php"); ?>
<?php 
$username = "";
$firstname = "";
if(isset($_GET['u'])){
$username = mysql_real_escape_string($_GET['u']);
if(ctype_alnum($username)){
    $check = mysql_query("SELECT username, first_name FROM users where username='$username' limit 1");
    $userCount = mysql_num_rows($check);
    if($userCount == 1){
        while($row = mysql_fetch_assoc($check)){
        $username = $row['username'];
        $firstname = $row['first_name'];
        }
    }else{
        echo "<meta http-equiv=\"refresh\" content=\"0; url=index.php\"> ";
        exit();
    }
 }
}
?>
<div id="Wrapper">
<div id="right">
    <div class="PostForm">

        <textarea id="post" name="post" rows="5" cols="180"></textarea>
        <!-- here is the submit button -->
        <input type="submit" name="send" onclick="javascript:send_post()" value="post" style="background-color:#DCE5EE;float:right;border:1px solid #666; color:#666;height:73px; width: 65px;">

    </div>
    <div class="profilePosts">YOur Posts will go Here</div>
</div>
<div id="left">
    <img src="" height="250" width="200" alt="<?php echo $username; ?>'s Profile" title="<?php echo $username; ?>'s Profile" />
    <br>
    <div class="textHeader"><?php echo $username; ?>'s Profile</div>
    <div class="profileLeftSideContent">Some Content about this persons profile..</div>
    <div class="textHeader"><?php echo $username; ?>'s Profile</div><br>
    <div class="profileLeftSideContent">
        <img src="#" height="50" width="40" />&nbsp;&nbsp;
        <img src="#" height="50" width="40" />&nbsp;&nbsp;
        <img src="#" height="50" width="40" />&nbsp;&nbsp;
        <img src="#" height="50" width="40" />&nbsp;&nbsp;
        <img src="#" height="50" width="40" />&nbsp;&nbsp;
        <img src="#" height="50" width="40" />&nbsp;&nbsp;
        <img src="#" height="50" width="40" />&nbsp;&nbsp;
        <img src="#" height="50" width="40" />&nbsp;&nbsp;
    </div>
</div>
</div>
<?php include('./inc/footer.inc.php'); ?>

the code for header.in.php file , i mentioned sorce of the javascript file correctly

<!Doctype html>
<html>
<head>
    <title>..</title>
    <link rel="stylesheet" type="text/css" href="./css/style.css">
    <script type="text/javascript" src="../js/main.js"></script>
</head>

the code for javascript file is , this function is doesnt loading while the submit button in the profile.php is called ..

function send_post() {
    var hr = new XMLHttpRequest();
    var url = "my_message_parse.php";
    var fn = document.getElementById("post").value;
    var vars = "post="+fn;
    hr.open("POST", url, true);
hr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
hr.onreadystatechange = function() {
    if(hr.readyState == 4 && hr.status == 200) {
        var return_data = hr.responseText;
        document.getElementById("status").innerHTML = return_data;
    }
}
hr.send(vars);
document.getElementById("status").innerHTML = "processing...";

}

is there any method withour using the javascript and please sepcify the error in the submit button of profile.php ,thanks for reply

The problem is it is a submit button so it submits the form onclick. You need to prevent that from happening.

<input type="submit" name="send" onclick="send_post(); return false;" ...

A better way would be to add the event unobtrusively and use preventDefault