[Javascript] Re: form validation

[Roger Roelofs]

Craig,

Before anything else, search the net for _good_ form validation 
scripts.  No sense re-inventing the wheel.   This will give you more 
robust code than if you roll your own.
--------------
First, I don't think you need the else clauses.  When a return 
statement is executed the function terminates.  So, maybe something 
like this

> function ValidateThis(formObj)	{
>  var totalcount = formObj.NumberOfTables.value;
>  var tableformat = formObj.TableFormat.value;
>  var chairscount = formObj.NumberOfChairs.value;
>  var chairsformat = formObj.ChairsFormat.value;
>  var housekeepingrequest = formObj.HousekeepingRequest.checked;
>  var hrd = formObj.HousekeepingRequestDate.value;
>
>  if (totalcount > 1 && tableformat == "Not applicable") {
>   alert("You must select a table format when you have requested 2 or 
> more tables.");
>   formObj.TableFormat.focus();
>   return false;
>  }
> if ((housekeepingrequest && hrd == "") || (housekeepingrequest &&
> (hrd.length != 10 || hrd.charAt(4) != '-' || hrd.charAt(7) != '-' ||
> (hrd.charAt(5) != 1 && hrd.charAt(5) != 0)))) {
>   alert("You have selected housekeeping request. Therefore you must 
> include
> a valid housekeeping request date in the format yyyy-mm-dd.");
>   formObj.HousekeepingRequest.focus();
>   return false;
>  }
....
Second,  I don't copy out all values into variables unless I'm going to 
to lots of manipulations, so for the formObj.TVVCR element (and others 
like it) I'd something like

if ( ! inRange( formObj.TVVCR,1,1,"TV/VCR") ) {
   return false;
}

where inRange( elem, low, high, label) is a function you write to turn 
the field into a number and check to see if it is an acceptable value 
and handle error conditions.

function inRange( elem, low, high, label) {
   var val = Number(elem.value);
   if ((val < low) || (val > high)) {
     alert("Please enter a value between " + low + " and " + high + " 
into the " + labal + " field.");
     elem.focus();
     return false;
   }
   return true;
}

On Tuesday, January 28, 2003, at 01:01  PM, 
javascript-request at LaTech.edu wrote:

> function ValidateThis(formObj)
> {
>  var totalcount = formObj.NumberOfTables.value;
>  var tableformat = formObj.TableFormat.value;
>  var chairscount = formObj.NumberOfChairs.value;
>  var chairsformat = formObj.ChairsFormat.value;
>  var housekeepingrequest = formObj.HousekeepingRequest.checked;
>  var hrd = formObj.HousekeepingRequestDate.value;
>  var tvvcr = formObj.TVVCR.value;
>
>  if (totalcount > 1 && tableformat == "Not applicable") {
>   alert("You must select a table format when you have requested 2 or 
> more
> tables.");
>   formObj.TableFormat.focus();
>   return false;
>  }
>
>  else if (chairscount > 1 && chairsformat == "Not applicable") {
>   alert("You must select a chairs format when you have requested 2 or 
> more
> chairs.");
>   formObj.ChairsFormat.focus();
>   return false;
>  }
>  else if ((housekeepingrequest && hrd == "") || (housekeepingrequest &&
> (hrd.length != 10 || hrd.charAt(4) != '-' || hrd.charAt(7) != '-' ||
> (hrd.charAt(5) != 1 && hrd.charAt(5) != 0)))) {
>   alert("You have selected housekeeping request. Therefore you must 
> include
> a valid housekeeping request date in the format yyyy-mm-dd.");
>   formObj.HousekeepingRequest.focus();
>   return false;
>  }
>  else if (tvvcr < 0 || tvvcr > 2) {
>   alert ("Invalid quantity of tv/vcr.");
>   formObj.TVVCR.focus();
>   return false;
>
>  }
>  else return true;
> }
>
> What I am realizing is that I have another 6 or 7 FORM fields that 
> need to
> be included in the data validation that are similar to tvvcr. I 
> suppose for
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