js-cfb/bits/04_base64.js

48 lines
1.5 KiB
JavaScript

var Base64 = (function make_b64(){
var map = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
return {
encode: function(input/*:string*/)/*:string*/ {
var o = "";
var c1/*:number*/, c2/*:number*/, c3/*:number*/;
var e1/*:number*/, e2/*:number*/, e3/*:number*/, e4/*:number*/;
for(var i = 0; i < input.length; ) {
c1 = input.charCodeAt(i++);
e1 = (c1 >> 2);
c2 = input.charCodeAt(i++);
e2 = ((c1 & 3) << 4) | (c2 >> 4);
c3 = input.charCodeAt(i++);
e3 = ((c2 & 15) << 2) | (c3 >> 6);
e4 = (c3 & 63);
if (isNaN(c2)) { e3 = e4 = 64; }
else if (isNaN(c3)) { e4 = 64; }
o += map.charAt(e1) + map.charAt(e2) + map.charAt(e3) + map.charAt(e4);
}
return o;
},
decode: function b64_decode(input/*:string*/)/*:string*/ {
var o = "";
var c1/*:number*/, c2/*:number*/, c3/*:number*/;
var e1/*:number*/, e2/*:number*/, e3/*:number*/, e4/*:number*/;
// eslint-disable-next-line no-useless-escape
input = input.replace(/[^\w\+\/\=]/g, "");
for(var i = 0; i < input.length;) {
e1 = map.indexOf(input.charAt(i++));
e2 = map.indexOf(input.charAt(i++));
c1 = (e1 << 2) | (e2 >> 4);
o += String.fromCharCode(c1);
e3 = map.indexOf(input.charAt(i++));
c2 = ((e2 & 15) << 4) | (e3 >> 2);
if (e3 !== 64) { o += String.fromCharCode(c2); }
e4 = map.indexOf(input.charAt(i++));
c3 = ((e3 & 3) << 6) | e4;
if (e4 !== 64) { o += String.fromCharCode(c3); }
}
return o;
}
};
})();