使用jQuery选择空文本输入 [英] Selecting empty text input using jQuery
问题描述
如何使用jQuery识别空文本框？我想做它使用选择器，如果它是在所有可能的。此外，我必须选择id，因为在实际代码中，我想使用这个我不想选择所有的文本输入。
How do I identify empty textboxes using jQuery? I would like to do it using selectors if it is at all possible. Also, I must select on id since in the real code where I want to use this I don't want to select all text inputs.
在我的下面两个代码示例第一个精确地显示由用户输入到文本框txt2中的值。第二个例子标识有一个空的文本框，但如果你填充它仍然认为它是空的。为什么是这样？
In my following two code examples the first one accurately displays the value typed into the textbox "txt2" by the user. The second example identifies that there is an empty textbox, but if you fill it in it still regards it as empty. Why is this?
这可以使用选择器完成吗？
Can this be done using just selectors?
此代码报告文本框中的值 txt2：
This code reports the value in textbox "txt2":
<html>
<head>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
<script type="text/javascript">
$(function() {
$('#cmdSubmit').click(function() {
alert($('[id=txt2]').val());
});
});
</script>
</head>
<body>
<form>
<input type="text" name="txt1" id="txt1" value="123" /><br />
<input type="text" name="txt2" id="txt2" value="" /><br />
<input type="text" name="txt3" id="txt3" value="abc" /><br />
<input type="submit" name="cmdSubmit" id='cmdSubmit' value="Send" /><br />
</form>
</body>
</html>
此代码总是将文本框txt2报告为空：
This code always reports textbox "txt2" as empty:
<html>
<head>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
<script type="text/javascript">
$(function() {
$('#cmdSubmit').click(function() {
if($('[id^=txt][value=""]').length > 0) {
if (!confirm("Are you sure you want to submit empty fields?")) {
if (event.preventDefault) {
event.preventDefault();
} else {
event.returnValue = false;
}
}
}
});
});
</script>
</head>
<body>
<form>
<input type="text" name="txt1" id="txt1" value="123" /><br />
<input type="text" name="txt2" id="txt2" value="" /><br />
<input type="text" name="txt3" id="txt3" value="abc" /><br />
<input type="submit" name="cmdSubmit" id='cmdSubmit' value="Send" /><br />
</form>
</body>
</html>
推荐答案
另一种方式
$('input:text').filter(function() { return $(this).val() == ""; });
或
$('input:text').filter(function() { return this.value == ""; });
或
// WARNING: if input element does not have the "value" attribute or this attribute was removed from DOM then such selector WILL NOT WORK!
// For example input with type="file" and file does not selected.
// It's prefer to use "filter()" method.
// Thanks to @AaronLS
$('input:text[value=""]');
jQuery
jQuery
$(function() {
$('#button').click(function() {
var emptyTextBoxes = $('input:text').filter(function() { return this.value == ""; });
var string = "The blank textbox ids are - \n";
emptyTextBoxes.each(function() {
string += "\n" + this.id;
});
alert(string);
});
});
这篇关于使用jQuery选择空文本输入的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
