要完成此效果需要两个步骤
第一步：把如下代码加入到<head>区域中
<script LANGUAGE="Javascript">
<!-- Begin
function NumToHex(num1,num2) {
strNum=document.forms[0].elements[num1].value;
for(i = 0; i < strNum.length; i++) {
chr=strNum.substring(i, i + 1);
if((isNaN(chr))||(chr == ‘ ‘)) {
alert(‘You must enter a digit between 0 and 9!‘);
document.forms[0].elements[num1].select();
document.forms[0].elements[num2].value=‘‘;
return false;
}
}
if(strNum > 255) {
alert(‘You must enter a number between 0 and 255!‘);
document.forms[0].elements[num1].select();
document.forms[0].elements[num2].value=‘‘;
return false;
}
else {
base = strNum / 16;
rem = strNum % 16;
base = base - (rem / 16);
baseS = MakeHex(base);
remS = MakeHex(rem);
document.forms[0].elements[num2].value=baseS + ‘‘ + remS;
ChangeBackground(3, 4, 5);
return true;
}
}
function MakeHex(x) {
if((x >= 0) && (x <= 9))
return x;
else {
switch(x) {
case 10: return "A";
case 11: return "B";
case 12: return "C";
case 13: return "D";
case 14: return "E";
case 15: return "F";
}
}
}
function HexToNum(num1,num2) {
numberS = document.forms[0].elements[num1].value;
tens = MakeNum(numberS.substring(0,1));
if(tens == ‘X‘) {
document.forms[0].elements[num1].select();
document.forms[0].elements[num2].value=‘‘;
return false;
}
ones = 0;
if(numberS.length > 1) // means two characters entered
ones=MakeNum(numberS.substring(1,2));
if(ones == ‘X‘) {
document.forms[0].elements[num1].select();
document.forms[0].elements[num2].value=‘‘;
return false;
}
document.forms[0].elements[num2].value = (tens * 16) + (ones * 1);
document.forms[0].elements[num1].value = document.forms[0].elements[num1].value.toUpperCase();
ChangeBackground(3, 4, 5);
return true;
}
function MakeNum(str) {
if((str >= 0) && (str <= 9))
return str;
switch(str.toUpperCase()) {
case "A": return 10;
case "B": return 11;
case "C": return 12;
case "D": return 13;
case "E": return 14;
case "F": return 15;
default: alert(‘You must choose a number between 0 and 9 or a letter between A and F!‘);
return ‘X‘;
}
}
function ChangeBackground(num1, num2, num3) {
document.bgColor = ‘#‘+document.forms[0].elements[num1].value + document.forms[0].elements[num2].value + document.forms[0].elements[num3].value;
}
// End -->
</script>
第二步：把代码加入到<body>区域中
<form>
<table border=0 align=center cellpadding=10 bgcolor=white>
<tr bgcolor="#000000">
<th><font color="#33FF33">Color/Code</font></th>
<th><font color="#33FF33">Red</font></th>
<th><font color="#33FF33">Green</font></th>
<th><font color="#33FF33">Blue</font></th>
</tr>
<tr bgcolor="#000000">
<th><font color="#33FF33">0-255</font></th>
<td>
<input type=text name=rr_num size=4 maxlength=3 onKeyUp="return NumToHex(0,3);"></td>
<td>
<input type=text name=gg_num size=4 maxlength=3 onKeyUp="return NumToHex(1,4);"></td>
<td>
<input type=text name=bb_num size=4 maxlength=3 onKeyUp="return NumToHex(2,5);"></td>
</tr>
<tr bgcolor="#000000">
<th><font color="#33FF33">HEX</font></th>
<td>
<input type=text name=rr_hex size=4 maxlength=2 onKeyUp="return HexToNum(3,0);">
</td>
<td>
<input type=text name=gg_hex size=4 maxlength=2 onKeyUp="return HexToNum(4,1);">
</td>
<td>
<input type=text name=bb_hex size=4 maxlength=2 onKeyUp="return HexToNum(5,2);"></td>
</tr>
</table>
</form>
