onchange value returning 'object HtmlFormElement'

[dfin]

I have a form where I need the text value to be passed to another form element later on.

 

Right now, it have

<form method='post' action='https://secure.autho...ay/transact.dll' >
<input type='text' name='amount' value='50.00' />
Change: <input type="checkbox" name="chg" onclick="myF(this.form)">
<script type="text/javascript">
function myF(val) {
var num = val;
var n = num.toString();
alert("You have now changed the amount to pay: " + n );
}
</script>
<input type='text' name='x_amount' value='<?php echo $_REQUEST['num'] ?>' />
<input type='Submit' value='Pay Now'>
</form>

It will then return the Alert box & in place of + n, it says object HtmlFormElement.

 

I tried doing a document.getElementById(this.form), but I think that gave me a null.

 

I know I will later need to do a validation to make sure it is a number & 2 decimals, but for now I need my alert & variable to be passed right.

 

I've tried  + n, + val, had it to where it didn't create the toString...nothing works

Edited June 11, 2015 by dfin

[CroNiX]

A few things.

 

1) you can't use getElementById() unless there is actually something with the ID. You're not using ANY ID's on any of your form elements so it won't work.

2) onclick="myF(this.form)" You're sending the ENTIRE form to myF(). That's why you're getting an "object" in the alert()

 

Try changing these lines:

//give this form field an ID of 'amount'
<input type='text' name='amount' value='50.00' id="amount" />
 
//no need to pass anything to the myF() function
Change: <input type="checkbox" name="chg" onclick="myF()">
 
<script type="text/javascript">
function myF() {
    //get value from the form field that has the id of 'amount'
    var amount = document.getElementById('amount').value;
    alert("You have now changed the amount to pay: " + amount );  //alerts 50.00 unless value changed
}
</script>

Edited June 11, 2015 by CroNiX

[dfin]

ahhh.. thanks so much.

I'm quite rusty and just getting back into this. i had some id's stuck here and there and didn't put em back with other trial and error's.

i have it now also submitting to the value of another input field also.