blobCompare

Compares two blobs by using arraybuffers

This is the default comparison method

Throw:

Test:

• Blob-compare bytesEqualWithArrayBuffer

Compares two blobs by using binary strings

This is not the default method to byte compare two blobs as benchmarks shows it's a little bit slower than using array buffers in most cases.

There's still at least two cases where using binary string is much faster :

• Empty blobs
• Blobs much prone to have difference at the start of the data

Test:

• Blob-compare bytesEqualWithBinaryString

Compares two buffers byte to byte

Test:

• Blob-compare compareBuffers

Compares two buffers byte through web worker

Compares two buffers byte to byte through main thread

Automatically compares two blobs by using the given methods

Allowed methods are with aliases :

• byte, bytes, content : Performs a byte comparison between the two blogs. The optional sizes option parameter can be used to provide sizes to perform comparison on sliced blobs. See blobCompare.bytesEqualWithArrayBuffer and blobCompare.bytesEqualWithBinaryString for more informations;
• magic, headers, numbers, mime : Compare two blobs based on magic numbers. See blobCompare.magicNumbersEqual for more informations;
• size, sizes : Compare two blobs based on their size in bytes. See blobCompare.sizeEqual for more informations;
• type, types : Compare two blobs based on their type. See blobCompare.typeEqual for more informations.

Using the partial option can be tricky as it's easy to have false positive.

As default, isEqual performs first a check on size method to discrimate blobs, then type, then magic and fallback on byte comparison on full data. This default order ensures the most optimized resource cost, though performing a complete comparison. For huge blobs, one may think about doing chunks comparison.

Workers can be disabled through options

Test:

• Blob-compare isEqual

Compares the magic numbers of two blobs

This method simply compare byte to byte at the start of data where magic numbers are usually located in most cases. You can find a quite exhaustive list of file signatures on wikipedia

It does not provide any informations about file type, but you can easily use a library like file-type to parse more informations about data if needed.

Be warned that this method can lead to false negative/positive for some file types given the currently naive algorithm.

Test:

• Blob-compare magicNumbersEqual

Compare size of two blobs

Obviously, two different blobs in content can have the same size and this method is only useful to discriminate blobs

Test:

• Blob-compare sizeEqual

Convert a blob to an ArrayBuffer

The blob can optionnally be sliced with the chunkargument

Test:

• Blob-compare toBinaryString && toArrayBuffer

Convert a blob to an ArrayBuffer through a web worker

The blob can optionnally be sliced with the chunkargument

Convert a blob to an ArrayBuffer through main thread

The blob can optionnally be sliced with the chunkargument

Convert a blob to a binary string

The blob can optionnaly be sliced with the chunk arguments

Test:

• Blob-compare toBinaryString && toArrayBuffer

Convert a blob to a binary string through a web worker thread

Convert a blob to a binary string through main thread

The blob can optionnaly be sliced with the chunk arguments

Compare type of two blobs

Never rely solely on this method to discriminate blobs or, worse, consider them as equal

Test:

• Blob-compare typeEqual