Base64 encoding and decoding in client-side Javascript

Question

Are there any methods in JavaScript that could be used to encode and decode a string using base64 encoding?

Answer 1

Here is a tightened up version of Sniper's post. It presumes well formed base64 string with no carriage returns. This version eliminates a couple of loops, adds the &0xff fix from Yaroslav, eliminates trailing nulls, plus a bit of code golf.

decodeBase64 = function(s) {
    var e={},i,b=0,c,x,l=0,a,r='',w=String.fromCharCode,L=s.length;
    var A="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    for(i=0;i<64;i++){e[A.charAt(i)]=i;}
    for(x=0;x=8){((a=(b>>>(l-=8))&0xff)||(x<(L-2)))&&(r+=w(a));}
    }
    return r;
};