我的ajax_form.php页面是：
<html><head>
<meta content="text/html;charset=utf-8" http-equiv="Content-Type">
<meta content="utf-8" http-equiv="encoding">
<script>
function showUser(form, e) {
e.preventDefault();
var xmlhttp;
var submit = form.getElementsByClassName('submit')[0];
var sent = document.getElementsByName('sent')[0].value || '';
var id = document.getElementsByName('id')[0].value || '';
if (sent==""){
document.getElementById("txtHint").innerHTML="";
return;
}
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(e) {
if (xmlhttp.readyState==4 && xmlhttp.status==200){
document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open(form.method, form.action, true);
xmlhttp.send('sent='+sent+'&id='+id+'&'+submit.name+'='+submit.value);
}
</script>
<form action="ajax_test.php" method="POST">
Enter the sentence: <input type="text" name="sent"><br>
<input type="submit" class="submit" name="insert" value="submit" onsubmit="showUser(this, event)">
</form>
<br>UPDATE <br>
<form action="ajax_test.php" method="POST" onsubmit="showUser(this, event)">
<pre>
Enter the ID : <input type="text" name="id"><br>
Enter the sentence: <input type="text" name="sent"><br>
</pre>
<input type="submit" class="submit" value="submit" name="update" >
</form> <br>
<div id="txtHint">
<b>Person info will be listed here.</b>
</div>
</body>
</html>
ajax_test.php为：
<html><head>
<meta content="text/html;charset=utf-8" http-equiv="Content-Type">
<meta content="utf-8" http-equiv="encoding">
</head> <body >
<?php
// $q = $_POST["q"];
// you never process the $q var so i commented it
if (isset($_POST['insert']) && $_POST['insert'] !== '') {
echo "Operation: Insert","<br>";
$s = $_POST['sent'];
$flag = 0;
echo "Entered sentence : $s";
if (preg_match_all('/[^=]*=([^;@]*)/',
shell_exec("/home/technoworld/Videos/LinSocket/client '$s'"),
$matches)){ //Values stored in ma.
$x = (int) $matches[1][0]; //optionally cast to int
$y = (int) $matches[1][1];
}
echo "<br>",
"Positive count :$x",
"<br>",
"Negative count :$y",
"<br>";
//---------------DB stuff --------------------
$con = mysqli_connect('127.0.0.1:3306', 'root', 'root', 'test');
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$sql1 = "INSERT INTO table2
(id,sent,pcount,ncount,flag)
VALUES
('','".$_POST['sent']."',' $x ','$y','$flag')";
if (mysqli_query($con, $sql1)) {
echo "1 record added";
} else {
die('Error: ' . mysqli_error($con));
}
mysqli_close($con);
}
// -------------------------------UPDATE --------------------------
if (isset($_POST['update']) && $_POST['update'] !== '') {
echo "Operation: update", "<br>";
// you say update but you are actually inserting below
$s = $_POST['sent'];
$flag = 1;
echo "Entered sentence : $s";
if (preg_match_all('/[^=]*=([^;@]*)/',
shell_exec("/home/technoworld/Videos/LinSocket/client '$s'"),
$matches)) //Values stored in ma.
{
$x = (int) $matches[1][0]; //optionally cast to int
$y = (int) $matches[1][1];
}
echo "<br>",
"Positive count :$x",
"<br>",
"Negative count :$y",
"<br>";
//---------------DB stuff --------------------
$con = mysqli_connect('127.0.0.1:3306', 'root', 'root', 'test');
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$sql1 = "INSERT INTO table2
(id,sent,pcount,ncount,flag)
VALUES
('','".$_POST['sent']."',' $x ','$y','$flag')"; // error here again $_POST[id] should be $_POST['id'] with quotes
if (mysqli_query($con, $sql1)) {
echo "1 record added";
} else {
die('Error: ' . mysqli_error($con));
}
mysqli_close($con);
}
?></html > </body >
在表1中，我把函数调用放在了按钮点击事件上，效果很好。但点击按钮，它加载页面并重定向到ajax_test.php。我们能说它正确使用了ajax吗？
在第二个表单中，我将函数调用保留在表单本身中，并根据脚本中的要求进行编码。但点击按钮就会发生动作。是错误的函数调用还是其他错误？
在这两种情况下，如何在不加载页面（刷新）的情况下显示结果？
问题出在sent参数上——它正在寻找一个名为"send"的输入，但该输入不存在。然后，如果未设置，则退出showUser函数。
以下是有问题的片段（我在下面删除了它）：
if (sent==""){
document.getElementById("txtHint").innerHTML="";
return;
}
除了这个问题之外，您还没有关闭</head>或打开<body>标记，这本身不是问题，而是一个相当大的格式问题。此外，请始终在<script>元素上放置一个type。最后，您应该以内联方式关闭<meta />、<input />和<br />元素。一致地格式化你的代码（兄弟元素在它们自己的行上，每个层次有4个空格的选项卡）可以帮助你发现一些小的格式化问题，比如缺少开放体等。
也就是说，这对我有效：
<html>
<head>
<meta content="text/html;charset=utf-8" http-equiv="Content-Type" />
<meta content="utf-8" http-equiv="encoding" />
<script type="text/javascript">
function showUser(form, e) {
e.preventDefault();
var xmlhttp;
var submit = form.getElementsByClassName('submit')[0];
var sent = document.getElementsByName('sent')[0].value || '';
var id = document.getElementsByName('id')[0].value || '';
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(e) {
if (xmlhttp.readyState == 4 && xmlhttp.status == 200){
document.getElementById("txtHint").innerHTML = xmlhttp.responseText;
}
}
xmlhttp.open(form.method, form.action, true);
xmlhttp.send('sent=' + sent + '&id=' + id + '&' + submit.name + '=' + submit.value);
}
</script>
</head>
<body>
<form action="ajax_test.php" method="POST" onsubmit="showUser(this, event)">
<label>Enter the sentence: <input type="text" name="sent"></label><br />
<input type="submit" class="submit" name="insert" value="submit" onsubmit="showUser(this, event)" />
</form>
<h4>UPDATE</h4>
<form action="ajax_test.php" method="POST" onsubmit="showUser(this, event)">
<pre>
<label>Enter the ID:</label>
<input type="text" name="id"><br>
<label>Enter the sentence:</label>
<input type="text" name="sent"><br>
</pre>
<input type="submit" class="submit" value="submit" name="update" />
</form>
<br />
<div id="txtHint">
<b>Person info will be listed here.</b>
</div>
</body>
</html>