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regarding calling javascript function from html form RSS

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Last post Mar 06, 2012 06:22 AM by Danny Gokey

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ogsim07

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regarding calling javascript function from html form

Mar 05, 2012 03:21 PM|LINK

Question at bottom of post.

html:-

<form id="form" name="myForm" method="post" action="" onsubmit="return(validate());">

javascript:-

function validate() {
if(document.myForm.name.value.length == 0){
       alert("Please enter Firstname");

       document.myForm.name.focus();
       return false;
   }

      var check = /^[A-Za-z ]{3,20}$/;

   if (!check.test(document.myForm.name.value))
      {
       alert("Firstname cannot contain numbers");
       document.myForm.name.focus();
       return false;
   }
}

</script>

Question:-

Why do we have to say onsubmit="return(validate());" ?? (it works correctly)

if I say onsubmit="validate();" then the page refreshes.. whats the difference?
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me_ritz

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1448 Posts

Re: regarding calling javascript function from html form

Mar 05, 2012 03:27 PM|LINK

onsubmit can be used to validate data in HTML forms before sending off the content to a server.

if validation fails, returing false from validation method must return to the page that stops it from posting.

hence, onsubmit="return(validate());" that returns false to page.

in case of onsubmit="validate();" even though validation fails, you return nothing to form to stop it from post.

http://www.w3schools.com/js/js_form_validation.asp

Please mark the post as "Answer" that helps you.
- Marked as answer by ogsim07 on Mar 06, 2012 10:21 AM
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roopeshreddy

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Re: regarding calling javascript function from html form

Mar 05, 2012 03:28 PM|LINK

Hi,

The return value is important there!

If you didn't return false, then it will consider that, the return value from the validate function is true!

NOTE: Default javascript function will return true.

Hence, if you didn't specify the return value - true/false, then it will consider true!

Then it will submit the page! If you wish to stop the submit behaviour then you have to return false incase of invalid form entries!

Hope it helps u...

Thanks & Regards
Roopesh Reddy C
Roopesh's Space
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ogsim07

Participant

967 Points

733 Posts

Re: regarding calling javascript function from html form

Mar 05, 2012 05:33 PM|LINK

i think i missed out a line in the code:_ i have made it bold below.

Even after including this line do i require the onsubmit="return(validate());" ?? or is onsubmit="validate();" enough ??

javascript:-

function validate() {
if(document.myForm.name.value.length == 0){
       alert("Please enter Firstname");

       document.myForm.name.focus();
       return false;
   }

      var check = /^[A-Za-z ]{3,20}$/;

   if (!check.test(document.myForm.name.value))
      {
       alert("Firstname cannot contain numbers");
       document.myForm.name.focus();
       return false;
   }

return true;
}

</script>
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me_ritz

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1448 Posts

Re: regarding calling javascript function from html form

Mar 06, 2012 02:54 AM|LINK

you require onsubmit="return validate();".

Please mark the post as "Answer" that helps you.
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Danny Gokey

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56 Posts

Re: regarding calling javascript function from html form

Mar 06, 2012 06:22 AM|LINK

Hi,

When you use the onsubmit="validate()", the validate() will retrun the ture or false , however, onsubmit attribute looks like a

mehod of a html, its value(the string) is the body of the method, and by default returns true, which equivalent to automatically

submit form and have already been validated

In summary, if form validation must be written like this: onsubmit= return function()

Hope it helps
- Edited by Danny Gokey on Mar 06, 2012 06:24 AM