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.
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?
Can this be done using just selectors?
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>
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>
This question is related to
jquery
css-selectors
Building on @James Wiseman's answer, I am using this:
$.extend($.expr[':'],{
blank: function(el){
return $(el).val().match(/^\s*$/);
}
});
This will catch inputs which contain only whitespace in addition to those which are 'truly' empty.
Example: http://jsfiddle.net/e9btdbyn/
You could also do it by defining your own selector:
$.extend($.expr[':'],{
textboxEmpty: function(el){
return $(el).val() === "";
}
});
And then access them like this:
alert($(':text:textboxEmpty').length); //alerts the number of text boxes in your selection
Since creating an JQuery object for every comparison is not efficient, just use:
$.expr[":"].blank = function(element) {
return element.value == "";
};
Then you can do:
$(":input:blank")
This will select empty text inputs with an id that starts with "txt":
$(':text[value=""][id^=txt]')
$("input[type=text][value=]")After trying a lots of version I found this the most logical.
Note that text is case-sensitive.
There are a lot of answers here suggesting something like [value=""] but I don't think that actually works . . . or at least, the usage is not consistent. I'm trying to do something similar, selecting all inputs with ids beginning with a certain string that also have no entered value. I tried this:
$("input[id^='something'][value='']")
but it doesn't work. Nor does reversing them. See this fiddle. The only ways I found to correctly select all inputs with ids beginning with a string and without an entered value were
$("input[id^='something']").not("[value!='']")
and
$("input[id^='something']:not([value!=''])")
but obviously, the double negatives make that really confusing. Probably, Russ Cam's first answer (with a filtering function) is the most clear method.
$(":text[value='']").doStuff();
?
By the way, your call of:
$('input[id=cmdSubmit]')...
can be greatly simplified and speeded up with:
$('#cmdSubmit')...
I'd recommend:
$('input:text:not([value])')
As mentioned in the top ranked post, the following works with the Sizzle engine.
$('input:text[value=""]');
In the comments, it was noted that removing the :text portion of the selector causes the selector to fail. I believe what's happening is that Sizzle actually relies on the browser's built in selector engine when possible. When :text is added to the selector, it becomes a non-standard CSS selector and thereby must needs be handled by Sizzle itself. This means that Sizzle checks the current value of the INPUT, instead of the "value" attribute specified in the source HTML.
So it's a clever way to check for empty text fields, but I think it relies on a behavior specific to the Sizzle engine (that of using the current value of the INPUT instead of the attribute defined in the source code). While Sizzle might return elements that match this selector, document.querySelectorAll will only return elements that have value="" in the HTML. Caveat emptor.
Source: Stackoverflow.com