function b64ToUint6 (nChr) { return nChr > 64 && nChr < 91 ? nChr - 65 : nChr > 96 && nChr < 123 ? nChr - 71 : nChr > 47 && nChr < 58 ? nChr + 4 : nChr === 43 ? 62 : nChr === 47 ? 63 : 0; } function base64ToArrayBuffer(sBase64, nBlockSize) { var sB64Enc = sBase64.replace(/[^A-Za-z0-9\+\/]/g, ""), nInLen = sB64Enc.length, nOutLen = nBlockSize ? Math.ceil((nInLen * 3 + 1 >>> 2) / nBlockSize) * nBlockSize : nInLen * 3 + 1 >>> 2, aBytes = new Uint8Array(nOutLen); for (var nMod3, nMod4, nUint24 = 0, nOutIdx = 0, nInIdx = 0; nInIdx < nInLen; nInIdx++) { nMod4 = nInIdx & 3; nUint24 |= b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << 18 - 6 * nMod4; if (nMod4 === 3 || nInLen - nInIdx === 1) { for (nMod3 = 0; nMod3 < 3 && nOutIdx < nOutLen; nMod3++, nOutIdx++) { aBytes[nOutIdx] = nUint24 >>> (16 >>> nMod3 & 24) & 255; } nUint24 = 0; } } return aBytes; }