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/**
* Create a blob builder even when vendor prefixes exist
*/
var BlobBuilder = global.BlobBuilder
|| global.WebKitBlobBuilder
|| global.MSBlobBuilder
|| global.MozBlobBuilder;
/**
* Check if Blob constructor is supported
*/
var blobSupported = (function() {
try {
var a = new Blob(['hi']);
return a.size === 2;
} catch(e) {
return false;
}
})();
/**
* Check if Blob constructor supports ArrayBufferViews
* Fails in Safari 6, so we need to map to ArrayBuffers there.
*/
var blobSupportsArrayBufferView = blobSupported && (function() {
try {
var b = new Blob([new Uint8Array([1,2])]);
return b.size === 2;
} catch(e) {
return false;
}
})();
/**
* Check if BlobBuilder is supported
*/
var blobBuilderSupported = BlobBuilder
&& BlobBuilder.prototype.append
&& BlobBuilder.prototype.getBlob;
/**
* Helper function that maps ArrayBufferViews to ArrayBuffers
* Used by BlobBuilder constructor and old browsers that didn't
* support it in the Blob constructor.
*/
function mapArrayBufferViews(ary) {
for (var i = 0; i < ary.length; i++) {
var chunk = ary[i];
if (chunk.buffer instanceof ArrayBuffer) {
var buf = chunk.buffer;
// if this is a subarray, make a copy so we only
// include the subarray region from the underlying buffer
if (chunk.byteLength !== buf.byteLength) {
var copy = new Uint8Array(chunk.byteLength);
copy.set(new Uint8Array(buf, chunk.byteOffset, chunk.byteLength));
buf = copy.buffer;
}
ary[i] = buf;
}
}
}
function BlobBuilderConstructor(ary, options) {
options = options || {};
var bb = new BlobBuilder();
mapArrayBufferViews(ary);
for (var i = 0; i < ary.length; i++) {
bb.append(ary[i]);
}
return (options.type) ? bb.getBlob(options.type) : bb.getBlob();
};
function BlobConstructor(ary, options) {
mapArrayBufferViews(ary);
return new Blob(ary, options || {});
};
module.exports = (function() {
if (blobSupported) {
return blobSupportsArrayBufferView ? global.Blob : BlobConstructor;
} else if (blobBuilderSupported) {
return BlobBuilderConstructor;
} else {
return undefined;
}
})();
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