在jQuery中使用.val（）时输入字段不存在
[英]Input Field not coming when using .val() in jquery
问题描述
I have a simple jquery and php program which is checking username availability. 
我有一个简单的jquery和php程序，用于检查用户名的可用性。 But when i am running this code it is not showing the input field. 但是，当我运行此代码时，它没有显示输入字段。 Here is my jquery 这是我的jQuery
<html>
<head>
<title>the title</title>
<script type="text/javascript"
src="js/jquery-1.4.1.min.js"></script>
<script type="text/javascript" language="javascript">
$(document).ready(function() {
$('#check').html(username);
$.post(
"user_availability.php",
{ username: $("#username").val()},
function(data) {
$('#check').html(data);
}
);
});
</script>
</head>
<body>
<div id="check">
</div><br><br>
<form>
<input type="text" id="username" name="username" value="rajan" /></form>
</html>
Please help me out as i am a beginner to jquery. 由于我是jquery的初学者，请帮助我。
4 个解决方案
解决方案1
2 已采纳 2014-06-13 11:34:00
Define Username ,Using keyup method send the data and get the result 定义Username ，使用keyup方法发送数据并获取结果
Try this 尝试这个
$(document).ready(function () {
var username = $("#username").val();
$('#check').html(username);
$('input:text').keyup(function () {
$.post(
"user_availability.php", {
username: $(this).val()
},
function (data) {
$('#check').html(data);
});
});
$('#username').trigger('keyup');//if you want to trigger keyup onload add this
});
解决方案2
1 2014-06-13 11:31:02
$(document).ready(function () {
var username = $("#username").val();
$('#check').html(username);
$.post(
"user_availability.php", {
username: username
},
function (data) {
$('#check').html(data);
}
);
});
解决方案3
1 2014-06-13 11:31:07
username is 用户名是
not
defined 定义的
while trying to pass as an argument 试图通过作为争论
$('#check').html(username); // <---
$.post(
"user_availability.php",
{ username: $("#username").val()},
function(data) {
$('#check').html(data);
});
});
and if you want to check everytime the input changes, you need to listen to it 如果您想每次输入更改时检查一下，就需要听一下
//keyup to check every time a character is entered
$('#username').keyup(function () {
$.post(
// on change, to only check when user blurs the field
$(document).on("change","#username",function () {
$.post(
解决方案4
0 2014-06-13 11:38:27
you can try this 你可以试试这个
<script>
$(document).ready(function() {
$('#check').html($("#username").prop('value'));
$.post(
"user_availability.php",
{ username: $("#username").val()},
function(data) {
$('#check').html(data);
});
}); }）;
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