Show me a Simple javascript onSubmit handler

Question

Hello again everyone i am working on this

Answer 1

OnSubmit is invoked once for the form.

You can validate all the form fields in one onSubmit function, during one call to that function.

function myOnSubmitHandler(theForm) { 
    if (theForm.data1.value == "") { 
        alert("This field is empty.");
        return false; // suppress form submission
    } else {
        return true; // A-OK, form will be submitted
    }
}

in HTML:

<form method="POST" ACTION="SomethingOnServer.php" 
      onSubmit="return myOnSubmitHandler(this);">

Answer 2

I need to have a onsubmit form handler

You said it; <form onsubmit="return myValidate(this);" .... >

myValidate is your validation function that returns true|false indicating whether or not you want the form to be submitted to its handler script (which your also missing).

Answer 3

I've added an example here of how to do it:

http://jsfiddle.net/tomgrohl/JMkAP/

I added an onsubmit handler to the form:

<form method="post" action="javascript" enctype="text/plain" onsubmit="return valForm(this);">

And added this at the top of the page, a simple validation function:

<script type="text/javascript">
function valForm( form ){

    var firstVal, lastVal, emailVal, error = '';

    firstVal= form.first.value;  
    lastVal= form.last.value;
    emailVal= form.email.value;

    //OR
    //firstVal= document.getElementById('first').value;  
    //lastVal= document.getElementById('last').value;
    //emailVal= document.getElementById('email').value;

    if( firstVal.length == 0){
        error += 'First name is required\n';
    }

    if( lastVal.length == 0){
        error += 'Last name is required\n';
    }

    if( emailVal.length == 0){
        error += 'Email is required\n';
    }

    if( error ){
        alert( error );
        return false;
    }

    return true;
}
</script>

Answer 4

might I suggest you use jQuery and jQuery validate to validate your form no need to re-invent the wheel

be sure to check out validator's demo