Canceling Form Submissions

[Compucles]

How do you get a form to not submit when it fails a validation check in a JavaScript function called from an OnClick event of the submit button?

[dsonesuk]

It is usually called from the 'onsubmit' of the form not 'onclick' of submit button as someone could submit by pressing the 'Enter' button, and so bypass the 'onclick' event.<form onsubmit="return valdatethis();" action="whateverpage.php" method="post">return will cause the function to run but wait for return value of 'true' to proceed, or 'false' to not proceed because data is not valid.function valdatethis(){var isvalid=true;//run code to validate codeif(....){isvalid=false;}if(....) { isvalid=false; }//if any fails the validation code in the if conditions above, the value for varible 'isvalid' will be set to false, else it will remain as true.//now all you have to do is return this varible valuereturn isvalid;}more detailed example shown here, slightly different but does the same thing.http://www.w3schools.com/js/js_form_validation.asp