Created
June 1, 2015 09:13
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base64 to blob
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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 base64DecToArr (sBase64, nBlocksSize) { | |
var | |
sB64Enc = sBase64.replace(/[^A-Za-z0-9\+\/]/g, ""), nInLen = sB64Enc.length, | |
nOutLen = nBlocksSize ? Math.ceil((nInLen * 3 + 1 >> 2) / nBlocksSize) * nBlocksSize : nInLen * 3 + 1 >> 2, taBytes = new Uint8Array(nOutLen); | |
for (var nMod3, nMod4, nUint24 = 0, nOutIdx = 0, nInIdx = 0; nInIdx < nInLen; nInIdx++) { | |
nMod4 = nInIdx & 3; | |
nUint24 |= b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << 6 * (3 - nMod4); | |
if (nMod4 === 3 || nInLen - nInIdx === 1) { | |
for (nMod3 = 0; nMod3 < 3 && nOutIdx < nOutLen; nMod3++, nOutIdx++) { | |
taBytes[nOutIdx] = nUint24 >>> (16 >>> nMod3 & 24) & 255; | |
} | |
nUint24 = 0; | |
} | |
} | |
return taBytes; | |
} | |
function b2b(sBase64, type) { | |
var arrayBuffer = base64DecToArr(sBase64); | |
type = type || 'text/plain'; | |
return new Blob([arrayBuffer], {type: type}); | |
} |
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