The following example will demonstrate a poll where the result is shown without reloading.
When a user choose an option above, a function called "getVote()" is executed. The function is triggered by the "onclick" event
<html>
<head>
<script type="text/javascript">
function getVote(int)
{
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("poll").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","poll_vote.php?vote="+int,true);
xmlhttp.send();
}
</script>
</head>
<body>
<div id="poll">
<h3>Do you like PHP and AJAX so far?</h3>
<form>
Yes:
<input type="radio" name="vote"value="0" onclick="getVote(this.value)" />
<br />No:
<input type="radio" name="vote"value="1" onclick="getVote(this.value)" />
</form>
</div>
</body>
</html>
The getVote() function does the following:
- Create an XMLHttpRequest object
- Create the function to be executed when the server response is ready
- Send the request off to a file on the server
- Notice that a parameter (vote) is added to the URL (with the value of the yes or no option)
判断控件的disabled属性是不是true，是的话return false;实现禁用radio的onclick事件并可再次启用它
方法一：（同时实现禁用，重新启用功能，只能针对button text类型的INPUT，对div无法禁用其onclick事件）
<input type="button" value="A button. Click me to see the alert box." onclick="alert('I am clicked.');" id="cmd1" />
<br/>
<input type="button" value="Click me to disable the first button" onclick="document.getElementById('cmd1').disabled=true;" />
<br/>
方法二，三：（实现移除radio的onclick事件，需再次重新注册事件，可以禁用div的onclick事件）
<input type="button" value="Click me to disable the onclick event on first button" onclick="document.getElementById('cmd1').onclick=function(){};" />
<br/>
三：
<input type="button" value="Click me to disable the onclick event on first button" onclick="document.getElementById('cmd1').onclick=null;" />
部分摘自 http://www.w3schools.com/