js 64编码

js 64编码

//   js 64编码
function base64_encode(str) {
	var base64encodechars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
        var out, i, len;
        var c1, c2, c3;
        len = str.length;
        i = 0;
        out = "";
        while (i < len) {
            c1 = str.charCodeAt(i++) & 0xff;
            if (i == len) {
                out += base64encodechars.charAt(c1 >> 2);
                out += base64encodechars.charAt((c1 & 0x3) << 4);
                out += "==";
                break;
            }
            c2 = str.charCodeAt(i++);
            if (i == len) {
                out += base64encodechars.charAt(c1 >> 2);
                out += base64encodechars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xf0) >> 4));
                out += base64encodechars.charAt((c2 & 0xf) << 2);
                out += "=";
                break;
            }
            c3 = str.charCodeAt(i++);
            out += base64encodechars.charAt(c1 >> 2);
            out += base64encodechars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xf0) >> 4));
            out += base64encodechars.charAt(((c2 & 0xf) << 2) | ((c3 & 0xc0) >> 6));
            out += base64encodechars.charAt(c3 & 0x3f);
        }
        return out;
}