HTML Attribute for <INPUT ...>
onKeyPress ="script command(s)"

Usage Recommendation
Use it, but don't rely on it.

Before reading through this page, you might want to check out these solutions first:

onKeyPress runs a JavaScript when the user presses a key. onKeyPress can be used to cancel the event so that the character is never entered in the field. onKeyPress also helps you to check which key was pressed, allowing for different actions based on different keys.

For our first example, this short form contains several radio buttons and a single text field. The text field is for the "Other" radio button. Typing data in the text field implies that the "Other" button should be checked, so we'll use onKeyPress to make it automatic. Using onKeyPress, when the user types something in the text field, the last option is automatically checked:

<FORM ACTION="/cgi-bin/mycgi.pl" METHOD=POST>
How did you hear about our company?<BR>
<INPUT TYPE=RADIO NAME="media" VALUE="internet">Internet<BR>
<INPUT TYPE=RADIO NAME="media" VALUE="newspaper">Newspaper<BR>
<INPUT TYPE=RADIO NAME="media" VALUE="tv">Television<BR>
<INPUT TYPE=RADIO NAME="media" VALUE="other">Other ...

<INPUT NAME="othermedia" onKeyPress="var m=this.form.media;m[m.length -1].checked=true"><BR>

<INPUT TYPE=SUBMIT VALUE="send it">
</FORM>

This gives us this form:

How did you hear about our company?
Internet
Newspaper
Television
Other ...
(Form is not live)

In the next page we discuss how to cancel the key press event.

Canceling the Key Press >