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>