Javascript 將字串轉成 binary 與 binary to string

 
function str2bin(str) {
    n = str.length;
    bin = "";
    for (var i = 0 ; i< n ; i++) {
        s = str.substr(i, 1);
        bin += str_pad(s.charCodeAt(0).toString(2), 8, "0", "left");
    }
    return bin;
}
 
function str_pad(str, len, chr, dir)
{/*{{{*/
    str = str.toString();
    len = (typeof len == "number") ? len : 0;
    chr = (typeof chr == "string") ? chr : " ";
    dir = (/left|right|both/i).test(dir) ? dir : "right";
    var repeat = function(c, l) {
 
        var repeat = "";
        while (repeat.length < l) {
            repeat += c;
        }
        return repeat.substr(0, l);
    }
    var diff = len - str.length;
    if (diff > 0) {
        switch (dir) {
            case "left":
                str = "" + repeat(chr, diff) + str;
                break;
            case "both":
                var half = repeat(chr, Math.ceil(diff / 2));
                str = (half + str + half).substr(1, len);
                break;
            default:
                str = "" + str + repeat(chr, diff);
        }
    }
    return str;
}/*}}}*/

function bin2str(text) {
    var output = "";
    for (var i = 0 ; i < text.length; i+= 8) {
        var c = 0;
        for (var j=0; j < 8 ; j++) {
            c <<= 1;
            c |= parseInt(text[i + j]);
        }
        output += String.fromCharCode(c);
    }
    return output;
}