javascript validation starter help

leonight · 02-23-2013, 02:37 PM

help me to find error in the below code

Code:

<html>
<head>
<title></title>

<script>
var user=document.getElementById('abcd');
function validate()
{
if (newa(user))
{
}
return false;
}

function newa(user)
{
var kks=user.value.length
if (kks==0)
{
document.getElementById('ablab').innerHTML="fdfsdfd";
return false;
}
}
</script>


</head>
<body>
<form action="" method="post" onsubmit="return validate()">
<input id="abcd" type="text">
<label id="ablab"></label>
</br>
<input type="submit">
</form>
</body>
</html>

sunfighter · 02-23-2013, 03:11 PM

What are you trying to do?

xelawho · 02-23-2013, 03:17 PM

you define the variable "user" before that element exists, so that will always fail.

either define it within the validate function (which will give it time to get created) or, better, put all of your script after your html, just before the closing /body tag

Philip M · 02-23-2013, 03:43 PM

You are going a long way round.

var kks=user.value.length
if (kks==0)

First of all, to assign the meaningless name kks to the length of the variable user is plain silly. Always assign meaningful names/ids. Such as uservaluelen. Likewise assigning an id of abcd for the textbox is also plain daft.

But there is no point in having an extra function - all you need is

Code:

<script type = "text/javascript">

function validate() {
document.getElementById('message').innerHTML = "";  // reset
var user = document.getElementById('username').value;
if (user.length) == 0 {
document.getElementById('message').innerHTML = "You must enter  your name";
// re-focus on the input field
return false;
}
}

</script>

Secondly, form validation of the pattern if (document.formname.formfield.value == "") (or length ==0) - that is blank - is barely worthy of the name, and virtually useless, as even a single space, an X or a ? will return false, that is pass the validation. A proper name may only contain letters, hyphen, space and apostrophe.
Numeric values, such as zip codes, phone numbers and dates, should be validated as such. Ditto email addresses. This topic has been covered many times before in this forum.

And Franco di Santo, who never scored here in his spell with Chelsea, threatened to do the same for the opposition. - Commentator BBC 1

Philip M · 02-23-2013, 05:09 PM

Quote:

Originally Posted by xelawho

you define the variable "user" before that element exists, so that will always fail.

either define it within the validate function (which will give it time to get created) or, better, put all of your script after your html, just before the closing /body tag

That won't do! Wherever the script is positioned it will attempt to evaluate

var user=document.getElementById('abcd');

before the user had had any time to enter his details.

You must define the variable user within the function.

But indeed scripts should be positioned in the page right in front of the </body> tag.

leonight · 02-24-2013, 08:04 AM

i am just practising don't suggest me how to write the code.....

i need your help to find error in above code.the code is not executing

Philip M · 02-24-2013, 10:43 AM

Quote:

Originally Posted by leonight

i am just practising don't suggest me how to write the code.....

i need your help to find error in above code.the code is not executing

You have been told very clearly why the code is not executing. And it is not a good reason for writing poor code with silly variable names to say that you are "just practising". As a leaner driver do you deliberately or carelessly drive badly when you are "just practising"?

If you want to learn anything and "need help" you should pay attention to the advice of experienced people. However:-

Code:

var rude = true;
var thanks = false;
if (rude && !thanks) {
var interestLost = true;
var moreHelp = 0;
}