64 .js

var codes = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-_".split('');

function to64(d) {
    var r = d % 64;
    var result;
    if (d - r == 0)
        result = codes[r];
    else
        result = to64((d - r) / 64) + codes[r];
    return result;
}


function from64(d) {
    var result = 0;
    d.split('').forEach(function (c, i) {
      	console.log(codes.indexOf(c), d.length - i);
    	result += (codes.indexOf(c)) * (((d.length - i - 1) * 64 ) || 1);
    });
    return result;
}