Generic clearForm function when click CLEAR button

[Matt]

I want to write a generic clearForm function to clear the form when
the user click CLEAR button.

Here's my attempts, because I want to take care all html controls. I
think I need to test
if the control is submit button, regular button. But I don't know
what I should do on drop down box?

function clearForm()
{ var i=0;
for (i=0; i<InputForm.ele ments.length-1; i++)
{ var obj = InputForm.eleme nts[i];
document.write( obj.type); //runtime error: object doesn't support
this property or method
if (obj.type != "submit" && obj.type != "button")
obj.value = "";
}
}

any ideas?? thanks!!

[Mick White]

Matt wrote:

I want to write a generic clearForm function to clear the form when
the user click CLEAR button.

Here's my attempts, because I want to take care all html controls. I
think I need to test
if the control is submit button, regular button. But I don't know
what I should do on drop down box?

function clearForm()
{ var i=0;
for (i=0; i<InputForm.ele ments.length-1; i++)
{ var obj = InputForm.eleme nts[i];
document.write( obj.type); //runtime error: object doesn't support
this property or method
if ()
obj.value = "";
}
}

any ideas?? thanks!!

function clearForm(form) {
f=form.length
for (i=0; i<f-1; i++){
obj=form[i];
if(obj.value && obj.type != "submit" && obj.type != "button"){
obj.value="";
}
}
}
You could hit "reset" button to do the same thing.
Mick

[bruce]

jr********@hotm ail.com (Matt) wrote in message news:<ba******* *************** ****@posting.go ogle.com>...

I want to write a generic clearForm function to clear the form when
the user click CLEAR button.

Here's my attempts, because I want to take care all html controls. I
think I need to test
if the control is submit button, regular button. But I don't know
what I should do on drop down box?

function clearForm()
{ var i=0;
for (i=0; i<InputForm.ele ments.length-1; i++)
{ var obj = InputForm.eleme nts[i];
document.write( obj.type); //runtime error: object doesn't support
this property or method
if (obj.type != "submit" && obj.type != "button")
obj.value = "";
}
}

any ideas?? thanks!!

Here's a function I wrote a zillion years ago. I offer it to you with
no guarantees, but maybe it will help you:

function ClearFields ()
{
var iIdx,iCount,oOb j,sRes,sType
iCount=document .forms(0).lengt h
for (iIdx=0;iIdx<iC ount;iIdx++)
{
oObj=document.f orms(0).item(iI dx)
sType=oObj.type .substring(0,5)
// alert("stype=" + oObj.type + " val=" + oObj.value)
if (sType=="selec" )
{
oObj.selectedIn dex=0
}
else
if (sType=="check" )
oObj.checked=fa lse
else
if (sType=="text")
oObj.value=""
else
if (sType=="radio" )
oObj.checked=tr ue
}
}

[bruce]

jr********@hotm ail.com (Matt) wrote in message news:<ba******* *************** ****@posting.go ogle.com>...

I want to write a generic clearForm function to clear the form when
the user click CLEAR button.

Here's my attempts, because I want to take care all html controls. I
think I need to test
if the control is submit button, regular button. But I don't know
what I should do on drop down box?

function clearForm()
{ var i=0;
for (i=0; i<InputForm.ele ments.length-1; i++)
{ var obj = InputForm.eleme nts[i];
document.write( obj.type); //runtime error: object doesn't support
this property or method
if (obj.type != "submit" && obj.type != "button")
obj.value = "";
}
}

any ideas?? thanks!!

as far as a select control, I have set the length to zero, thereby
eliminating all the <option> items in the select control.

[Richard Cornford]

bruce wrote:
<snip>

function ClearFields ()
{
var iIdx,iCount,oOb j,sRes,sType
iCount=document .forms(0).lengt h
Treating the - document.forms - collection as a function, calling it and
passing an argument, is a Microsoftism and should not be expected to
work on non-IE browsers (though it does on some as they are forced to
put effort in to emulating IE's non-standard behaviour to accommodate
script authors who aren't interested in other browsers).

Normal (cross-browser) references to forms through the -
document.forms - collection would use a bracket notation property
accessor, and work on every browser that understands what a form is,
including IE.

iCount = document.forms[0].length;
for (iIdx=0;iIdx<iC ount;iIdx++)
{
oObj=document.f orms(0).item(iI dx)
Re-resolving the reference to the form within a loop is inefficient, and
treating the FORM element as implementing a HTMLCollection interface is
relying on a non-specified coincidence that, although it is common in
implementations , should not be relied upon.

The controls within a from are traditionally, and by W3C HTML DOM
specification, available as indexed members of the FORM's - elements -
collection, and can be reliably accessed through that collection on
every browser that understands what a form is:-

var elsRef, oObj, sType;
if((document.fo rms)&&
((elsRef = document.forms[0]))&&
((elsRef = elsRef.elements ))){

for(var c = elsRef.length;c--;){
oObj = elsRef[c];
sType= (new String(oObj.typ e)).substring(0 ,5);
if(sType=="sele c"){
...
... //etc.

}
}
}

Doing it this way also means that when the function is to be applied in
a different context, to a form with a different index, there is only one
place in the function where the index needs to be updated. Though a more
general function would be passed the from reference as an argument.
sType=oObj.type .substring(0,5)
// alert("stype=" + oObj.type + " val=" + oObj.value)
if (sType=="selec" )
{
oObj.selectedIn dex=0
}
If a SELECT element is select-multiple then setting its -
selectedIndex - to zero will not necessarily have the desired result.
else
if (sType=="check" )
oObj.checked=fa lse
else
if (sType=="text")
oObj.value=""
else
if (sType=="radio" )
oObj.checked=tr ue
}
What happened to TEXTAREA elements?
}

[Matt Kruse]

Matt wrote:

I want to write a generic clearForm function to clear the form when
the user click CLEAR button.

What does "clear" mean, exactly?
In input controls, it's obvious - setting the value to ''

But what about other controls:
- Checkbox: Does it mean unchecking all checkboxes, or checking only
boxes where value='' ?
- Radio: You can't uncheck all radio buttons in a group, so which one
stays selected?
- Select: Do you select the option with value='' ? What if there are
none?
- Multi-select: Do you unselect all options, or select options with
value='' ?
- File: You can't set the value of these at all!

In order to program to requirements, the requirements need to be clear :)

--
Matt Kruse
Javascript Toolbox: http://www.mattkruse.com/javascript/