javascript ASCII和Hex互转

<script>

var symbols = " !\"#$%&'()*+,-./0123456789:;<=>?@";
var loAZ = "abcdefghijklmnopqrstuvwxyz";
symbols+= loAZ.toUpperCase();
symbols+= "[\\]^_`";
symbols+= loAZ;
symbols+= "{|}~";

//Hex to ASCII
function toAscii(str)
{
valueStr = str.toLowerCase();
var hex = "0123456789abcdef";
var text = "";
var i=0;

for( i=0; i<valueStr.length; i=i+2 )
{
var char1 = valueStr.charAt(i);
if ( char1 == ':' )
{
i++;
char1 = valueStr.charAt(i);
}
var char2 = valueStr.charAt(i+1);
var num1 = hex.indexOf(char1);
var num2 = hex.indexOf(char2);
var value = num1 << 4;
value = value | num2;

var valueInt = parseInt(value);
var symbolIndex = valueInt - 32;
var ch = '?';
if ( symbolIndex >= 0 && value <= 126 )
{
ch = symbols.charAt(symbolIndex)
}
text += ch;
}
return text;
}
//ASCII to Hex
function toHex(str)
{
var valueStr = str;
var hexChars = "0123456789abcdef";
var text = "";
for( i=0; i<valueStr.length; i++ )
{
var oneChar = valueStr.charAt(i);
var asciiValue = symbols.indexOf(oneChar) + 32;
var index1 = asciiValue % 16;
var index2 = (asciiValue - index1)/16;
if ( text != "" ) text += ":";
text += hexChars.charAt(index2);
text += hexChars.charAt(index1);
}
return text;
}

</script>