[javascript] js base64 encode / js base64 decode

 (function() {
    window.btoa || (
    window.btoa = function(input) {
        var chars = ‘ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=’;
        var str = String (input);
        for (var block, charCode, idx = 0, map = chars, output = ”;
            str.charAt (idx | 0) || (map = ‘=’, idx % 1);
            output += map.charAt (63 & block >> 8 – idx % 1 * 8)) {
            charCode = str.charCodeAt (idx += 3 / 4);
            if (charCode > 0xFF) {
                alert(“btoa failed : The string to be encoded contains characters outside of the Latin1 range.”);
                return input;
            }
            block = block << 8 | charCode;
        }
        return output;
    });

    window.atob || (
    window.atob = function(input) {
        var chars = ‘ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=’;
        var str = (String (input)).replace (/[=]+$/, ”);
        if (str.length % 4 === 1) {
            alert(“atob failed : The string to be decoded is not correctly encoded.”);
            return input;
        }
        for (var bc = 0, bs, buffer, idx = 0, output = ”;
            buffer = str.charAt (idx++);
            ~buffer && (bs = bc % 4 ? bs * 64 + buffer : buffer, bc++ % 4) ? output += String.fromCharCode (255 & bs >> (-2 * bc & 6)) : 0) {
            buffer = chars.indexOf (buffer);
        }
        return output;
    });
} ());

function encodeBase64(_str) {
    return btoa(encodeURIComponent(_str));
}
   
function decodeBase64(_str) {
    return decodeURIComponent(atob(_str));
}