The Doc Dialer: Implementing the Keypad

The Doc Dialer

Implementing the Keypad

The phone keypad is built as a 3x4 table, mimicking a real phone faceplate. Each cell of the table contains an INPUT button. Let's look at one of the buttons, say 4:

<INPUT NAME="button4" TYPE="BUTTON" VALUE=" 4 GHI " onclick="numPressed(4)">

The button specification includes the VALUE of the button (the text printed on it), its NAME, and its onclick event handling. The event handling is the numPressed() function. Each button is sending a number between 0 to 11. The key itself is sent for keys 0 to 9. The asterix (*) button is sending a value of 10 and the pound sign (#) is sending a value of 11. The whole table is positioned within a FORM element, to facilitate the buttons inside. Here is the form:

<FORM NAME="phonePlate">
<TABLE BORDER=2 WIDTH=150 HEIGHT=60 CELLPADDING=1 CELLSPACING=5>
<TR>
  <TD><INPUT NAME="button1" TYPE="BUTTON" VALUE=" 1       "
       onclick="numPressed(1)"></TD>
  <TD><INPUT NAME="button2" TYPE="BUTTON" VALUE=" 2 ABC "
       onclick="numPressed(2)"></TD>
  <TD><INPUT NAME="button3" TYPE="BUTTON" VALUE=" 3 DEF "
       onclick="numPressed(3)"></TD>
  <TD ROWSPAN="4" VALIGN="top" NOWRAP><SPAN ID="foundSoFar"></SPAN></TD>
</TR>
<TR>
  <TD><INPUT NAME="button4" TYPE="BUTTON" VALUE=" 4 GHI "
       onclick="numPressed(4)"></TD>
  <TD><INPUT NAME="button1" TYPE="BUTTON" VALUE=" 5 JKL  "
       onclick="numPressed(5)"></TD>
  <TD><INPUT NAME="button1" TYPE="BUTTON" VALUE=" 6 MNO"
       onclick="numPressed(6)"></TD>
</TR>
<TR>
  <TD><INPUT NAME="button7" TYPE="BUTTON" VALUE=" 7 PRS"
       onclick="numPressed(7)"></TD>
  <TD><INPUT NAME="button8" TYPE="BUTTON" VALUE=" 8 TUV "
       onclick="numPressed(8)"></TD>
  <TD><INPUT NAME="button9" TYPE="BUTTON" VALUE=" 9 WXY"
       onclick="numPressed(9)"></TD>
</TR>
<TR>
  <TD><INPUT NAME="button*" TYPE="BUTTON" VALUE=" *        "
       onclick="numPressed(10)"></TD>
  <TD><INPUT NAME="button0" TYPE="BUTTON" VALUE=" 0        "
       onclick="numPressed(0)"></TD>
  <TD><INPUT NAME="button#" TYPE="BUTTON" VALUE=" #        "
       onclick="numPressed(11)"></TD>
</TR>
</TABLE>
</FORM>

The display on the right hand side of the keypad is created by a fourth column of the table, spanning all four rows, and including a SPAN element:

<SPAN ID="foundSoFar"></SPAN>

Produced by Yehuda Shiran and Tomer Shiran

Created: February 14, 2000
Revised: March 15, 2000

URL: https://www.webreference.com/js/column57/5.html