Topic awaiting preservation: Sending form field to js function

Greets!
I'm working on the window.open script generator, and I've hit a snag....

I have this function:
function changeValue(myValue,myChange){
if (designWindow.myValue.value == ""){
designWindow.myValue.value = 0;
}
designWindow.myValue.value = parseInt(designWindow.myValue.value) + myChange;
}

And I call it via:

<input type="button" value="+" onclick="changeValue('height',1);" />

So it "should" be setting designWindow.height.value = designWindow.height.value+1

But it's alerting "designWindow.myValue.value is null or not an object". I tried sending the value without the single quotes, but that didn't fix anything. What's up with that? If I hard code the form field name, it works fine, but defeats my purpose for having a function.

You're passing string parameter as myValue, and therefore designWindow.myValue.value won't be designWindow.height.value as expected, since it's basically designWindow.'height'.value and that's invalid (string doesn't represent property). You have two options, use eval() to assemble appropriate line of code, or modify your function to look something like this:

function changeValue(myField, myChange)
{
&nbsp;&nbsp;&nbsp;&nbsp;if (myField.value == "")
&nbsp;&nbsp;&nbsp;&nbsp;{
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;myField.value = 0;
&nbsp;&nbsp;&nbsp;&nbsp;}
&nbsp;&nbsp;&nbsp;&nbsp;myField.value = parseInt(myField.value) + myChange;
}

And then call it like this:

<input type="button" value="+" onclick="changeValue(this.height,1);" />

BTW <input> button must be located in the same form as height field, since I'm using "this" reserved word to reference parent form...




[This message has been edited by mr.maX (edited 02-25-2002).]

One needn't use eval() to make a string represent a property. You only need to use the [] operator, like this:

designWindow[myValue].value

Doh, I completely forgot about that... It ain't easy knowing syntax of all those language in your head in each moment, heh...

Anyway, Pugzly, if you settle with [] operator, don't forget to add "document." part in front of "designWindow[myValue].value" (i.e. "document.designWindow[myValue].value"), because that's how forms are supposed to be referenced...

Bingo...as always, you guys know the answers..

Thanks!