How to validate an element is exist in form or not using JS
Question
<pre>
<script>
// here i want to check form validation
//if i use for loop txtbox2 is not exist in my form so i am getting Js error
//Don't write individual validation
//check element is exist or not if exist check for validation
//I need know how to check an element is exist or not
</script>
<form
<input type="text" id="txtbox1" name="txtbox1" />*
<input type="text" id="txtbox3" name="txtbox3" />*
<input type="text" id="txtbox4" name="txtbox4" />*
<input type="text" id="txtbox5" name="txtbox5" />*
<input type="text" id="txtbox15" name="txtbox15" />*
<input type="text" id="txtbox28" name="txtbox28" />*
</pre>
3 answers
solution1
2 ACCPTED 2011-02-27 08:10:44
Apply a class to them:
<input type="text" id="txtbox1" name="txtbox1" class="txt" />
<input type="text" id="txtbox3" name="txtbox3" class="txt" />
<input type="text" id="txtbox4" name="txtbox4" class="txt" />
<input type="text" id="txtbox5" name="txtbox5" class="txt" />
<input type="text" id="txtbox15" name="txtbox15" class="txt" />
<input type="text" id="txtbox28" name="txtbox28" class="txt" />
and go about like this:
function validate(){
var elms = document.getElementsByTagName('input');
for (var i = 0; i < elms.length; i++){
if (elms[i].className === 'txt'){
if (elms[i].value === ''){
alert('Make sure to fill in all required fields');
// now focus it
elms[i].focus();
return false;
}
}
}
return true;
}
And then call the above function like this:
<form ............ onsubmit="return validate();">
solution2
2 2011-02-27 08:16:10
Post your code.
Easiest way to validate is by using jquery validate plugin.(Why write your own code when somebody else has done the same?).
An example
<script type="text/javascript" src="http://code.jquery.com/jquery-1.5.1.js"></script>
<script type="text/javascript" src="http://ajax.microsoft.com/ajax/jquery.validate/1.7/jquery.validate.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$("#feedbackform").validate();
});
</script>
<body>
<form id = "feedbackform" method = "POST" action = "">
<h3><span>Contact Us</span></h3>
<fieldset>
<legend>Contact form</legend>
<label for="id_name">Name *</label>
<input id="id_name" class="required" type="text" name="name" />
<label for="id_email">Email</label>
<input id="id_email" type="email" name="email" class="email"/>
<label for="id_comments">Message *</label>
<textarea id="id_comments" class="required" name="comments"></textarea>
<button type="submit">Send</button>
</fieldset>
</form>
The elements that you want to validate add class="required". I hope the example provided is self-explainatory
solution3
1 2011-02-27 08:10:21
You can get a reference to the element and check if the reference is null or not:
for (var i=1; i<=100; i++) {
var elem = document.getElementById('txtbox' + i);
if (elem != null) {
...
}
}
Another approach is to look at the elements in the form, but then you need a way to access the form of course:
var elems = document.getElementById('IdOfTheForm').elements;
for (var i=0; i<elems.length; i++) {
var elem = elems[i];
if (elem.tagName == 'INPUT' && elem.type == 'text' && elem.id.length > 6 && elemt.id.substr(0,6) == 'txtbox') {
...
}
}
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