Detecting keystorokes that "matter"

epigram

I have a form on a web page that contains several textbox controls (i.e.
input type="text") and a checkbox. As soon as the text changes, in only a
subset of these textbox controls, I want to enable the checkbox. I've tried
the OnChange event for these textbox controls, but this event is fired only
when the control loses focus. I need the checkbox to enable immediately. I
then started experimenting with the OnKeyUp event for these controls, and it
works but it picks up many keystrokes that really don't matter (e.g. Tab,
Esc, Shift). In othe words, I am only concerned with keystrokes that can
actually change the text in the control.

I tried filtering by key code and only considering codes between 32 and 127,
inclusive, and 8 (for the back space key), but this still picks up keys like
the left arrow. In this case, the keycode appears to be 37 which is the %
character. I'm not sure why this is.

In any case, I don't have to take this OnKeyUp type of approach if someone
has a better technique. In the end, I just want to enable a checkbox as
soon as text starts to change in one of these controls. Any help on
accomplishing this would be greatly appreciated.

Thanks!

Jul 23 '05 #1

Subscribe Post Reply

1220

> In the end, I just want to enable a checkbox as

soon as text starts to change in one of these controls. Any help on
accomplishing this would be greatly appreciated.

I'm not sure what exact rules are, you may change this script to make
it more narrow.

<html>
<head>
<title>Keystokes</title>
<meta http-equiv="Content-Type" content="text/html;
charset=iso-8859-1">
<script type="text/javascript">
function test(box) {
if(!box.memory) {
box.memory = "";
};
if ((box.value != box.memory)||(box.value != "")) {
alert("Text changed");
}
else {
alert("Test did not change");
}
}
</script>
</head>

<body bgcolor="#FFFFFF">
<form method="post" action="">
<input type="text" name="textfield1" onkeyup="test(this)">
</form>
</body>
</html>

Jul 23 '05 #2

Lee

epigram said:

I have a form on a web page that contains several textbox controls (i.e.
input type="text") and a checkbox. As soon as the text changes, in only a
subset of these textbox controls, I want to enable the checkbox. I've tried
the OnChange event for these textbox controls, but this event is fired only
when the control loses focus. I need the checkbox to enable immediately.

You're going to a lot of trouble and adding potential sources of
error to your page because you believe that you need the checkbox
to enable immediately. I would start by revisiting that idea.

It would be much easier (and safer) to leave the checkboxes enabled.
Your server-side code is going to be smart enough to ignore any
checkboxes corresponding to empty fields, isn't it?

Jul 23 '05 #3

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