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我需要显示一个基于用户输入的对话框，并且我正在实现Zebra对话框插件来帮助解决这个问题。Javascript变量，设置为HTML对象，总是返回空
当用户点击一个按钮时，我可以得到一个通用的对话框，但无论我做什么，我都无法使用Javascript来查看HTML文本框，更不用说其中的数据了。
我为此创建了一个测试页面。见下文。
下面是HTML/PHP代码（的index.php）：
<head>
<!-- Style for Zebra Dialog boxes -->
<link rel="stylesheet" href="zebra/zebra_dialog.css" type="text/css">
</head>
<header>
<h1>Testing My Dialogs and Alerts</h1>
</header>
<body>
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
$myTyping = trim($_POST["myTyping"]);
// Display what the user typed in a dialog. Is there some code that needs to go here?
}
?>
<form id="form_to_submit" action="index.php" method="POST">
<fieldset>
<label>Type anything you want:</label>
<input type="text" name="myTyping" id="myTyping">
<button type="submit" id="click">Click Here to show alert and see what you typed.</button>
</fieldset>
</form>
<!-- Link to jQuery file so any plug-ins can work
Including the production version here. Can also download one for better debugging. -->
<script type="text/javascript" src="jquery-1.12.0.min.js"></script>
<!-- Link to Zebra Dialog box code -->
<script type="text/javascript" src="zebra_dialog.js"></script>
<!-- Link to My Javascript code -->
<script type="text/javascript" src="myTestScripts.js"></script>
</body>
这里是Javascript代码（myTestScripts.js）。我已经尝试了3种不同的方式来获取用户的输入并显示它，但“getElementById”从不起作用。它还没有呈现？我试着把防止默认代码放进去，但这没有什么区别。
/* javascripts */
// FIRST TRY
$(document).ready(function() {
// show a dialog box when clicking on a button
$("#click").bind('click', function(e) {
//e.preventDefault();
$.Zebra_Dialog('The link was clicked!');
**var myInputElement = document.getElementById("myTyping"), // This doesn't get the element, always is null**
myInput = myInputElement.innerText;
console.log("myInputElement: " + myInputElement);
console.log("myInput: " + myInput);
$.Zebra_Dialog('Here is what you typed:', myInput);
});
});
// SECOND TRY
$('#form_to_submit').submit(function(e) {
console.log("inside form_to_submit");
**var myInputElement = document.getElementById("myTyping"), // also returns null**
myInput = myInputElement.innerText;
console.log("myInputElement: " + myInputElement);
console.log("myInput: " + myInput);
$.Zebra_Dialog('Here is what you typed:', myInput);
console.log("leaving form_to_submit");
});
// THIRD TRY
window.onsubmit = function (e) {
console.log("inside window.onsubmit, preventing default");
//e.preventDefault();
**var myInputElement = document.getElementById("myTyping"), // also returns null**
myInput = myInputElement.innerText;
console.log("myInputElement: " + myInputElement);
console.log("myInput: " + myInput);
$.Zebra_Dialog('Here is what you typed:', myInput);
console.log("leaving window.onsubmit");
}
当然！谢谢你的发现。 –