Problem creating an expression with variables

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Problem creating an expression with variables

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blcArmadillo
Samurai++

Joined: 04 Mar 2005
Posts: 85
Location: Michigan

Posted: Wed Jul 25, 2007 6:24 pm Post subject: Problem creating an expression with variables

I'm trying to make a simple function right now. I pass the form name and name of the input field I am targeting with the code:

Code:

onClick="clearfield('addboat', 'byear');"

This information passed to the function would than be used similar to the code listed below:

Code:

function clearfield(frm,fld) {
var ele = document.frm.fld;
alert(ele.value);
}

But, it appears as though document.frm.fld looks to a form called frm and an input field named fld rather than replacing the frm and fld with the information passed to the function. Can anyone tell me what I'm doing wrong? I can't seem to find anything online that shows me the correct syntax. Thanks.

WannaBe
Wiggles

Joined: 22 Oct 2004
Posts: 714
Location: CA

Posted: Thu Jul 26, 2007 2:41 pm Post subject:

something like this could work:

Code:

onclick="clearfield(document.addboat.byear);"

Code:

function clearfield(fieldItem)
{
var itemValue = fieldItem.value;
alert(itemValue)
}

Complete code (I used to test):

Code:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
   <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
   <title>Alert IT</title>
   <script>
function clearfield(fieldItem)
{
var itemValue = fieldItem.value;
alert(itemValue)
}
   </script>
</head>
<body>
<form name="addboat">
<input name="byear" type="text" value="" />
<input type="button" value="Alert Value" onclick="clearfield(document.addboat.byear);" />
</form>
</body>
</html>

but if you do want to pass the names as strings, you could do a search in the document.forms array for the form named that then search in the found form for the field name.

Ankou
Spam Mod

Joined: 22 Oct 2004
Posts: 1201
Location: Wisconsin

Posted: Sun Jul 29, 2007 5:14 pm Post subject: Re: Problem creating an expression with variables

blcArmadillo wrote:

I can't seem to find anything online that shows me the correct syntax. Thanks.

I'll post this again (I left the link in the other post you had): http://www.onlinetools.org/articles/unobtrusivejavascript/chapter2.html

The link if to chapter 2 but read the whole thing. It does a great job of letting you know how to get what you're after. The best part is that it's pretty well written and once you understand it you'll be set for DOM playing of all sorts.

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