90 lines
2.5 KiB
Markdown
90 lines
2.5 KiB
Markdown
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# Javascript implementation of xxHash
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## Synopsis
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xxHash is a very fast hashing algorithm (see the details [here](https://code.google.com/p/xxhash/)). xxhashjs is a Javascript implementation of it, written in 100% Javascript. Although not as fast as the C version, it does perform pretty well given the current Javascript limitations in handling unsigned 32 bits integers.
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## Installation
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In nodejs:
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npm install xxhashjs
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In the browser, include the following, and access the constructor with _XXH_:
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```javascript
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<script src="/your/path/to/xxhash.js"></script>
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```
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## Examples
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* In one step:
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```javascript
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var h = XXH.h32( 'abcd', 0xABCD ).toString(16) // seed = 0xABCD
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```
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> 0xCDA8FAE4
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* In several steps (useful in conjunction of NodeJS streams):
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```javascript
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var H = XXH.h32( 0xABCD ) // seed = 0xABCD
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var h = H.update( 'abcd' ).digest().toString(16)
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```
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> 0xCDA8FAE4
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* More examples in the examples directory:
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* Compute xxHash from a file data
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* Use xxHashjs in the browser
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## Usage
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* XXH makes 2 functions available for 32 bits XXH and 64 bits XXH respectively, with the same signature:
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* XXH.h32
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* XXH.h64
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* In one step:
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`XXH.h32(<data>, <seed>)`
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The data can either be a string, an ArrayBuffer or a NodeJS Buffer object.
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The seed can either be a number or a UINT32 object.
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* In several steps:
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* instantiate a new XXH object H:
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`XXH.h32(<seed>)` or `XXH.h32()`
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The seed can be set later on with the `init` method
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* add data to the hash calculation:
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`H.update(<data>)`
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* finish the calculations:
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`H.digest()`
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The object returned can be converted to a string with `toString(<radix>)` or a number `toNumber()`.
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Once `digest()` has been called, the object can be reused. The same seed will be used or it can be changed with `init(<seed>)`.
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## Methods
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* `XXH.h32()`
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* `.init(<seed>)`
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Initialize the XXH object with the given seed. The seed can either be a number or a UINT32 object.
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* `.update(<data>)`
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Add data for hashing. The data can either be a string, an ArrayBuffer or a NodeJS Buffer object.
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* `digest()` (_UINT32_)
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Finalize the hash calculations and returns an UINT32 object. The hash value can be retrieved with toString(<radix>).
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* `XXH.h64()`
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* `.init(<seed>)`
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Initialize the XXH object with the given seed. The seed can either be a number or a UINT64 object.
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* `.update(<data>)`
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Add data for hashing. The data can either be a string, an ArrayBuffer or a NodeJS Buffer object.
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* `.digest()` (_UINT64_)
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Finalize the hash calculations and returns an UINT64 object. The hash value can be retrieved with toString(<radix>).
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## License
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MIT
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