function changeBgcolor() {
var bg = document.getElementById('bg');
bg.style.backgroundColor = "#"
+ document.getElementById('rgb').rval.options[document.getElementById('rgb').rval.selectedIndex].value
+ document.getElementById('rgb').rval.options[document.getElementById('rgb').rval.selectedIndex].value
+ document.getElementById('rgb').gval.options[document.getElementById('rgb').gval.selectedIndex].value
+ document.getElementById('rgb').gval.options[document.getElementById('rgb').gval.selectedIndex].value
+ document.getElementById('rgb').bval.options[document.getElementById('rgb').bval.selectedIndex].value
+ document.getElementById('rgb').bval.options[document.getElementById('rgb').bval.selectedIndex].value;
}
document.write("<table><tr><td>");
document.write("<form id=\"rgb\">");
document.write("<table style=\"margin:1em 0;\">");
document.write("<tbody><tr>");
document.write("<th style=\"background : red ; color :white; border:1px solid black;\">R</th>");
document.write("<th style=\"background : green ; color :white; border:1px solid black;\">G</th>");
document.write("<th style=\"background : blue ; color :white; border:1px solid black;\">B</th>");
document.write("</tr><tr><td>");
document.write("<select onchange=\"changeBgcolor()\" size=\"6\" name=\"rval\">");
document.write("<option value=\"F\" selected=\"selected\">F</option><option value=\"C\">C</option><option value=\"9\">9</option><option value=\"6\">6</option><option value=\"3\">3</option><option value=\"0\">0</option>");
document.write("</select>");
document.write("</td><td>");
document.write("<select onchange=\"changeBgcolor()\" size=\"6\" name=\"gval\">");
document.write("<option value=\"F\" selected=\"selected\">F</option><option value=\"C\">C</option><option value=\"9\">9</option><option value=\"6\">6</option><option value=\"3\">3</option><option value=\"0\">0</option>");
document.write("</select>");
document.write("</td><td>");
document.write("<select onchange=\"changeBgcolor()\" size=\"6\" name=\"bval\">");
document.write("<option value=\"F\" selected=\"selected\">F</option><option value=\"C\">C</option><option value=\"9\">9</option><option value=\"6\">6</option><option value=\"3\">3</option><option value=\"0\">0</option>");
document.write("</select>");
document.write("</td></tr></tbody></table>");
document.write("</form>");
document.write("</td><td style=\"width:500px;\"><div id=\"bg\" style=\"height:150px; border:1px solid #999; background:#fff; margin:0;\"></div></td>");
document.write("</tr></table>");