document.bgColor = "#16進制色碼值" （例如白色為 #FFFFFF）

function NumToHex(num1,num2) {
  strNum=document.CT.elements[num1].value;
  base = strNum / 16;
  rem = strNum % 16;
  base = base - (rem / 16);
  baseS = MakeHex(base);
  remS = MakeHex(rem);
  document.CT.elements[num2].value=baseS + '' + remS;
  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";  
    }
  }
}

十六進制值轉十進制：

function HexToNum(num1,num2) {
  numberS = document.CT.elements[num1].value;
  tens = MakeNum(numberS.substring(0,1));
  ones = 0;
  if(numberS.length > 1) ones=MakeNum(numberS.substring(1,2));
  document.CT.elements[num2].value = (tens * 16) + (ones * 1);
  document.CT.elements[num1].value = document.CT.elements[num1].value.toUpperCase();
  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;
  }
}

☆ 小恐龍工作坊 製