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资源说明：DataView. Extended. Anywhere.
[](https://gitter.im/jDataView/jDataView?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
[](https://travis-ci.org/jDataView/jDataView)
[](https://npmjs.org/package/jdataview)
[jDataView](http://blog.vjeux.com/2011/javascript/jdataview-read-binary-file.html) - A unique way to work with a binary file in JavaScript.
================================
jDataView provides convenient way to read and/or modify binary data in all the browsers. It follows the [DataView Specification](http://www.khronos.org/registry/typedarray/specs/latest/#8) and even extends it for a more practical use.
Explanation
===========
There are three ways to read a binary file from the browser.
* The first one is to download the file through XHR with [charset=x-user-defined](https://developer.mozilla.org/en/using_xmlhttprequest#Receiving_binary_data). You get the file as a **String**, convert it to byte **Array** and you have to rewrite all the decoding and encoding functions (getUint16, getFloat32, ...). All the browsers support this.
* Then browsers that implemented **Canvas** also added **CanvasPixelArray** as part of **ImageData**. It is fast byte array that is created and used internally by `` element for manipulating low-level image data. We can create such host element and use it as factory for our own instances of this array.
* Then browsers that implemented **WebGL** added **ArrayBuffer**. It is a plain buffer that can be read with views called **TypedArrays** (Int32Array, Float64Array, ...). You can use them to decode the file but this is not very handy. It has big drawback, it can't read non-aligned data (but we can actually hack that). So they replaced **CanvasPixelArray** with **Uint8ClampedArray** (same as Uint8Array, but cuts off numbers outside 0..255 range).
* A new revision of the specification added **DataViews**. It is a view around your buffer that can read/write arbitrary data types directly through functions: getUint32, getFloat64 ...
And one way to read a binary file from the server.
* **NodeJS Buffers**. They appeared in [Node 0.4.0](http://nodejs.org/docs/v0.4.0/api/buffers.html). [Node 0.5.0](http://nodejs.org/docs/v0.5.0/api/buffers.html) added a DataView-like API. And [Node 0.6.0](http://nodejs.org/docs/v0.6.0/api/buffers.html) changed the API naming convention.
**jDataView** provides the **DataView API** with own convenient extensions using the best available option between Arrays, TypedArrays, NodeJS Buffers and DataViews.
Documentation
=============
* API
* [jDataView constructor](https://github.com/jDataView/jDataView/wiki/jDataView-constructor)
* [DataView Specification](http://www.khronos.org/registry/typedarray/specs/latest/#8)
* Extended Specification
* [Operation control](https://github.com/jDataView/jDataView/wiki/Operation-control)
* [writeXXX methods](https://github.com/jDataView/jDataView/wiki/writeXXX-methods)
* [Strings and Blobs](https://github.com/jDataView/jDataView/wiki/Strings-and-Blobs)
* [64-bit integers](https://github.com/jDataView/jDataView/wiki/64-bit-integers)
* [Bitfields](https://github.com/jDataView/jDataView/wiki/Bitfields)
* [Internal utilities](https://github.com/jDataView/jDataView/wiki/Internal-utilities)
* [Example](https://github.com/jDataView/jDataView/wiki/Example)
* [Changelog](https://github.com/jDataView/jDataView/blob/master/CHANGELOG.md)
Advanced usage ([jBinary](https://github.com/jDataView/jBinary))
========================
For complicated binary structures, it may be hard enough to use only low-level get/set operations for parsing,
processing and writing data.
In addition, most likely you might need convenient I/O methods for retrieving data from external sources such like
local files (using File API or from Node.js), remote files (via HTTP(S)), data-URIs, Node.js streams etc. as well
as for displaying generated content to user on webpage in image/video/audio/... containers
or even as simple download link.
If you faced any of these problems, you might want to check out new [jBinary](https://github.com/jDataView/jBinary)
library that works on top of **jDataView** and allows to operate with binary data in structured and convenient way.
Demos
=====
[HTTP Live Streaming realtime converter and player demo](http://rreverser.github.io/mpegts/) implemented using [jBinary](https://github.com/jDataView/jBinary) data structures.
[](http://rreverser.github.io/mpegts/)
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A [World of Warcraft Model Viewer](http://jdataview.github.io/jsWoWModelViewer/). It uses [jDataView](https://github.com/jDataView/jDataView)+[jBinary](https://github.com/jDataView/jBinary) to read the binary file and then WebGL to display it.
[](http://jdataview.github.io/jsWoWModelViewer/)
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A [PhotoSynth WebGL Viewer](http://www.visual-experiments.com/2011/04/05/photosynth-webgl-viewer/) by Visual Experiments. It uses jDataView to read the binary file and then WebGL to display it.
[](http://www.visual-experiments.com/2011/04/05/photosynth-webgl-viewer/)
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A [simple tar viewer](http://jdataview.github.io/jDataView/untar/). It is a "Hello World" demo of how easy it is to use the library.
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JavaScript [TrueTypeFont library demo](http://ynakajima.github.io/ttf.js/demo/glyflist/) which uses jDataView to read and display glyphs from TrueType file.
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[jBinary.Repo](https://jdataview.github.io/jBinary.Repo) ready-to-use typesets and corresponding demos of using
[jDataView](https://github.com/jDataView/jDataView)+[jBinary](https://github.com/jDataView/jBinary)
for reading popular file formats like
[GZIP archives](https://jdataview.github.io/jBinary.Repo/demo/#gzip),
[TAR archives](https://jdataview.github.io/jBinary.Repo/demo/#tar),
[ICO images](https://jdataview.github.io/jBinary.Repo/demo/#ico),
[BMP images](https://jdataview.github.io/jBinary.Repo/demo/#bmp),
[MP3 tags](https://jdataview.github.io/jBinary.Repo/demo/#mp3)
etc.
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[Talking image](http://hacksparrow.github.io/talking-image/) - animation and audio in one package powered by
HTML5 Audio, [jDataView](https://github.com/jDataView/jDataView) and [jBinary](https://github.com/jDataView/jBinary).
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*Please tell us if you made something with jDataView :)*
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