Error checking PHP or Javascript?

Anon

Hi,

I posted earlier but I'm still not sure.
I have a dbase enabled website which uses HTML forms. Should I use Javascript(client?) or PHP(server?) to validate them?

If I was to use Javascript, when the submit button is pressed, how would I get it to use the javascript instead of going straight to the PHP processing script (the one located in the form header) and ignoring it?

All I want to do is make sure that all fields have been filled in and on one filed, check it is a number.

Thanks-you.

Anon

The advantage of javascript is that the user doesn't have to wait for the complete page to reload. If you use javascript you have to validate again anyway to protect against malicious users. Javascript isn't always very portable across browsers if that's a concern. The validating with javascript would be with a onClick='validate_form()', but I would suggest reading a javascript book if you don't know much about it.

maxpup979

I agree with Roel for the most part. The portability of JS really isnt an issue in form validation, since virtually all of the JS you use is both MS and NN compatible. The big disadvantage to JS, is of course if the user has it turned off. Then the validation never occurs, and you could end up with a mess in the DB. But the advantages are just as Roel said.

This is the kind of code I use for validation:
<head>
function validate(form){
if (form.fieldname.value==""){
alert('you must fill out field fieldname');
form.fieldname.focus();
return false;
}
if(isNaN(form.fieldname2.value)){
//isNaN stands for is Not a Number
alert('you must fill out field fieldname2');
form.fieldname2.focus();
return false;
}
return true;
}

</head>

......
......
other stuff here
......
<form name = "frmnamewhatever" action="yadda.html" method = "post">
<input type = "text" name = "fieldname" value = "">
<input type = "text" name = "fieldname2" value = "">
<input type = "submit" name = "submit" value = "Submit" onClick="javascript: return validate(frmnamewhatever);">
</form>

Hope this does the trick. I wont guarentee the above JS, but Im pretty sure it should do the trick

Good luck!
Darren

Anon

Never use javascript to validate any variables that will need to later be placed into a database, if you do your database will be wide open to hackers.