twitst4tz

twitter statistics web application
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index.js (2531B)

      1 /**
      2  * Create a blob builder even when vendor prefixes exist
      3  */
      4 
      5 var BlobBuilder = typeof BlobBuilder !== 'undefined' ? BlobBuilder :
      6   typeof WebKitBlobBuilder !== 'undefined' ? WebKitBlobBuilder :
      7   typeof MSBlobBuilder !== 'undefined' ? MSBlobBuilder :
      8   typeof MozBlobBuilder !== 'undefined' ? MozBlobBuilder : 
      9   false;
     10 
     11 /**
     12  * Check if Blob constructor is supported
     13  */
     14 
     15 var blobSupported = (function() {
     16   try {
     17     var a = new Blob(['hi']);
     18     return a.size === 2;
     19   } catch(e) {
     20     return false;
     21   }
     22 })();
     23 
     24 /**
     25  * Check if Blob constructor supports ArrayBufferViews
     26  * Fails in Safari 6, so we need to map to ArrayBuffers there.
     27  */
     28 
     29 var blobSupportsArrayBufferView = blobSupported && (function() {
     30   try {
     31     var b = new Blob([new Uint8Array([1,2])]);
     32     return b.size === 2;
     33   } catch(e) {
     34     return false;
     35   }
     36 })();
     37 
     38 /**
     39  * Check if BlobBuilder is supported
     40  */
     41 
     42 var blobBuilderSupported = BlobBuilder
     43   && BlobBuilder.prototype.append
     44   && BlobBuilder.prototype.getBlob;
     45 
     46 /**
     47  * Helper function that maps ArrayBufferViews to ArrayBuffers
     48  * Used by BlobBuilder constructor and old browsers that didn't
     49  * support it in the Blob constructor.
     50  */
     51 
     52 function mapArrayBufferViews(ary) {
     53   return ary.map(function(chunk) {
     54     if (chunk.buffer instanceof ArrayBuffer) {
     55       var buf = chunk.buffer;
     56 
     57       // if this is a subarray, make a copy so we only
     58       // include the subarray region from the underlying buffer
     59       if (chunk.byteLength !== buf.byteLength) {
     60         var copy = new Uint8Array(chunk.byteLength);
     61         copy.set(new Uint8Array(buf, chunk.byteOffset, chunk.byteLength));
     62         buf = copy.buffer;
     63       }
     64 
     65       return buf;
     66     }
     67 
     68     return chunk;
     69   });
     70 }
     71 
     72 function BlobBuilderConstructor(ary, options) {
     73   options = options || {};
     74 
     75   var bb = new BlobBuilder();
     76   mapArrayBufferViews(ary).forEach(function(part) {
     77     bb.append(part);
     78   });
     79 
     80   return (options.type) ? bb.getBlob(options.type) : bb.getBlob();
     81 };
     82 
     83 function BlobConstructor(ary, options) {
     84   return new Blob(mapArrayBufferViews(ary), options || {});
     85 };
     86 
     87 if (typeof Blob !== 'undefined') {
     88   BlobBuilderConstructor.prototype = Blob.prototype;
     89   BlobConstructor.prototype = Blob.prototype;
     90 }
     91 
     92 module.exports = (function() {
     93   if (blobSupported) {
     94     return blobSupportsArrayBufferView ? Blob : BlobConstructor;
     95   } else if (blobBuilderSupported) {
     96     return BlobBuilderConstructor;
     97   } else {
     98     return undefined;
     99   }
    100 })();