jiaojiu/node_modules/buffer

buffer

The buffer module from node.js, for the browser.

With browserify, simply require('buffer') or use the Buffer global and you will get this module.

The goal is to provide an API that is 100% identical to node's Buffer API. Read the official docs for the full list of properties, instance methods, and class methods that are supported.

features

• Manipulate binary data like a boss, in all browsers -- even IE6!
• Super fast. Backed by Typed Arrays (Uint8Array/ArrayBuffer, not Object)
• Extremely small bundle size (5.04KB minified + gzipped, 35.5KB with comments)
• Excellent browser support (IE 6+, Chrome 4+, Firefox 3+, Safari 5.1+, Opera 11+, iOS, etc.)
• Preserves Node API exactly, with one minor difference (see below)
• Square-bracket buf[4] notation works, even in old browsers like IE6!
• Does not modify any browser prototypes or put anything on window
• Comprehensive test suite (including all buffer tests from node.js core)

install

To use this module directly (without browserify), install it:

npm install buffer

This module was previously called native-buffer-browserify, but please use buffer from now on.

A standalone bundle is available here, for non-browserify users.

usage

The module's API is identical to node's Buffer API. Read the official docs for the full list of properties, instance methods, and class methods that are supported.

As mentioned above, require('buffer') or use the Buffer global with browserify and this module will automatically be included in your bundle. Almost any npm module will work in the browser, even if it assumes that the node Buffer API will be available.

To depend on this module explicitly (without browserify), require it like this:

var Buffer = require('buffer/').Buffer  // note: the trailing slash is important!

To require this module explicitly, use require('buffer/') which tells the node.js module lookup algorithm (also used by browserify) to use the npm module named buffer instead of the node.js core module named buffer!

how does it work?

The Buffer constructor returns instances of Uint8Array that have their prototype changed to Buffer.prototype. Furthermore, Buffer is a subclass of Uint8Array, so the returned instances will have all the node Buffer methods and the Uint8Array methods. Square bracket notation works as expected -- it returns a single octet.

The Uint8Array prototype remains unmodified.

one minor difference

In old browsers, buf.slice() does not modify parent buffer's memory

If you only support modern browsers (specifically, those with typed array support), then this issue does not affect you. If you support super old browsers, then read on.

In node, the slice() method returns a new Buffer that shares underlying memory with the original Buffer. When you modify one buffer, you modify the other. Read more.

In browsers with typed array support, this Buffer implementation supports this behavior. In browsers without typed arrays, an alternate buffer implementation is used that is based on Object which has no mechanism to point separate Buffers to the same underlying slab of memory.

You can see which browser versions lack typed array support here.

tracking the latest node api

This module tracks the Buffer API in the latest (unstable) version of node.js. The Buffer API is considered stable in the node stability index, so it is unlikely that there will ever be breaking changes. Nonetheless, when/if the Buffer API changes in node, this module's API will change accordingly.

related packages

• buffer-equals - Node.js 0.12 buffer.equals() ponyfill
• buffer-reverse - A lite module for reverse-operations on buffers
• buffer-xor - A simple module for bitwise-xor on buffers
• is-buffer - Determine if an object is a Buffer without including the whole Buffer package
• typedarray-to-buffer - Convert a typed array to a Buffer without a copy

performance

See perf tests in /perf.

BrowserBuffer is the browser buffer module (this repo). Uint8Array is included as a sanity check (since BrowserBuffer uses Uint8Array under the hood, Uint8Array will always be at least a bit faster). Finally, NodeBuffer is the node.js buffer module, which is included to compare against.

NOTE: Performance has improved since these benchmarks were taken. PR welcoem to update the README.

Chrome 38

Method	Operations	Accuracy	Sampled	Fastest
BrowserBuffer#bracket-notation	11,457,464 ops/sec	±0.86%	66	✓
Uint8Array#bracket-notation	10,824,332 ops/sec	±0.74%	65
BrowserBuffer#concat	450,532 ops/sec	±0.76%	68
Uint8Array#concat	1,368,911 ops/sec	±1.50%	62	✓
BrowserBuffer#copy(16000)	903,001 ops/sec	±0.96%	67
Uint8Array#copy(16000)	1,422,441 ops/sec	±1.04%	66	✓
BrowserBuffer#copy(16)	11,431,358 ops/sec	±0.46%	69
Uint8Array#copy(16)	13,944,163 ops/sec	±1.12%	68	✓
BrowserBuffer#new(16000)	106,329 ops/sec	±6.70%	44
Uint8Array#new(16000)	131,001 ops/sec	±2.85%	31	✓
BrowserBuffer#new(16)	1,554,491 ops/sec	±1.60%	65
Uint8Array#new(16)	6,623,930 ops/sec	±1.66%	65	✓
BrowserBuffer#readDoubleBE	112,830 ops/sec	±0.51%	69	✓
DataView#getFloat64	93,500 ops/sec	±0.57%	68
BrowserBuffer#readFloatBE	146,678 ops/sec	±0.95%	68	✓
DataView#getFloat32	99,311 ops/sec	±0.41%	67
BrowserBuffer#readUInt32LE	843,214 ops/sec	±0.70%	69	✓
DataView#getUint32	103,024 ops/sec	±0.64%	67
BrowserBuffer#slice	1,013,941 ops/sec	±0.75%	67
Uint8Array#subarray	1,903,928 ops/sec	±0.53%	67	✓
BrowserBuffer#writeFloatBE	61,387 ops/sec	±0.90%	67
DataView#setFloat32	141,249 ops/sec	±0.40%	66	✓

Firefox 33

Method	Operations	Accuracy	Sampled	Fastest
BrowserBuffer#bracket-notation	20,800,421 ops/sec	±1.84%	60
Uint8Array#bracket-notation	20,826,235 ops/sec	±2.02%	61	✓
BrowserBuffer#concat	153,076 ops/sec	±2.32%	61
Uint8Array#concat	1,255,674 ops/sec	±8.65%	52	✓
BrowserBuffer#copy(16000)	1,105,312 ops/sec	±1.16%	63
Uint8Array#copy(16000)	1,615,911 ops/sec	±0.55%	66	✓
BrowserBuffer#copy(16)	16,357,599 ops/sec	±0.73%	68
Uint8Array#copy(16)	31,436,281 ops/sec	±1.05%	68	✓
BrowserBuffer#new(16000)	52,995 ops/sec	±6.01%	35
Uint8Array#new(16000)	87,686 ops/sec	±5.68%	45	✓
BrowserBuffer#new(16)	252,031 ops/sec	±1.61%	66
Uint8Array#new(16)	8,477,026 ops/sec	±0.49%	68	✓
BrowserBuffer#readDoubleBE	99,871 ops/sec	±0.41%	69
DataView#getFloat64	285,663 ops/sec	±0.70%	68	✓
BrowserBuffer#readFloatBE	115,540 ops/sec	±0.42%	69
DataView#getFloat32	288,722 ops/sec	±0.82%	68	✓
BrowserBuffer#readUInt32LE	633,926 ops/sec	±1.08%	67	✓
DataView#getUint32	294,808 ops/sec	±0.79%	64
BrowserBuffer#slice	349,425 ops/sec	±0.46%	69
Uint8Array#subarray	5,965,819 ops/sec	±0.60%	65	✓
BrowserBuffer#writeFloatBE	59,980 ops/sec	±0.41%	67
DataView#setFloat32	317,634 ops/sec	±0.63%	68	✓

Safari 8

Method	Operations	Accuracy	Sampled	Fastest
BrowserBuffer#bracket-notation	10,279,729 ops/sec	±2.25%	56	✓
Uint8Array#bracket-notation	10,030,767 ops/sec	±2.23%	59
BrowserBuffer#concat	144,138 ops/sec	±1.38%	65
Uint8Array#concat	4,950,764 ops/sec	±1.70%	63	✓
BrowserBuffer#copy(16000)	1,058,548 ops/sec	±1.51%	64
Uint8Array#copy(16000)	1,409,666 ops/sec	±1.17%	65	✓
BrowserBuffer#copy(16)	6,282,529 ops/sec	±1.88%	58
Uint8Array#copy(16)	11,907,128 ops/sec	±2.87%	58	✓
BrowserBuffer#new(16000)	101,663 ops/sec	±3.89%	57
Uint8Array#new(16000)	22,050,818 ops/sec	±6.51%	46	✓
BrowserBuffer#new(16)	176,072 ops/sec	±2.13%	64
Uint8Array#new(16)	24,385,731 ops/sec	±5.01%	51	✓
BrowserBuffer#readDoubleBE	41,341 ops/sec	±1.06%	67
DataView#getFloat64	322,280 ops/sec	±0.84%	68	✓
BrowserBuffer#readFloatBE	46,141 ops/sec	±1.06%	65
DataView#getFloat32	337,025 ops/sec	±0.43%	69	✓
BrowserBuffer#readUInt32LE	151,551 ops/sec	±1.02%	66
DataView#getUint32	308,278 ops/sec	±0.94%	67	✓
BrowserBuffer#slice	197,365 ops/sec	±0.95%	66
Uint8Array#subarray	9,558,024 ops/sec	±3.08%	58	✓
BrowserBuffer#writeFloatBE	17,518 ops/sec	±1.03%	63
DataView#setFloat32	319,751 ops/sec	±0.48%	68	✓

Node 0.11.14

Method	Operations	Accuracy	Sampled	Fastest
BrowserBuffer#bracket-notation	10,489,828 ops/sec	±3.25%	90
Uint8Array#bracket-notation	10,534,884 ops/sec	±0.81%	92	✓
NodeBuffer#bracket-notation	10,389,910 ops/sec	±0.97%	87
BrowserBuffer#concat	487,830 ops/sec	±2.58%	88
Uint8Array#concat	1,814,327 ops/sec	±1.28%	88	✓
NodeBuffer#concat	1,636,523 ops/sec	±1.88%	73
BrowserBuffer#copy(16000)	1,073,665 ops/sec	±0.77%	90
Uint8Array#copy(16000)	1,348,517 ops/sec	±0.84%	89	✓
NodeBuffer#copy(16000)	1,289,533 ops/sec	±0.82%	93
BrowserBuffer#copy(16)	12,782,706 ops/sec	±0.74%	85
Uint8Array#copy(16)	14,180,427 ops/sec	±0.93%	92	✓
NodeBuffer#copy(16)	11,083,134 ops/sec	±1.06%	89
BrowserBuffer#new(16000)	141,678 ops/sec	±3.30%	67
Uint8Array#new(16000)	161,491 ops/sec	±2.96%	60
NodeBuffer#new(16000)	292,699 ops/sec	±3.20%	55	✓
BrowserBuffer#new(16)	1,655,466 ops/sec	±2.41%	82
Uint8Array#new(16)	14,399,926 ops/sec	±0.91%	94	✓
NodeBuffer#new(16)	3,894,696 ops/sec	±0.88%	92
BrowserBuffer#readDoubleBE	109,582 ops/sec	±0.75%	93	✓
DataView#getFloat64	91,235 ops/sec	±0.81%	90
NodeBuffer#readDoubleBE	88,593 ops/sec	±0.96%	81
BrowserBuffer#readFloatBE	139,854 ops/sec	±1.03%	85	✓
DataView#getFloat32	98,744 ops/sec	±0.80%	89
NodeBuffer#readFloatBE	92,769 ops/sec	±0.94%	93
BrowserBuffer#readUInt32LE	710,861 ops/sec	±0.82%	92
DataView#getUint32	117,893 ops/sec	±0.84%	91
NodeBuffer#readUInt32LE	851,412 ops/sec	±0.72%	93	✓
BrowserBuffer#slice	1,673,877 ops/sec	±0.73%	94
Uint8Array#subarray	6,919,243 ops/sec	±0.67%	90	✓
NodeBuffer#slice	4,617,604 ops/sec	±0.79%	93
BrowserBuffer#writeFloatBE	66,011 ops/sec	±0.75%	93
DataView#setFloat32	127,760 ops/sec	±0.72%	93	✓
NodeBuffer#writeFloatBE	103,352 ops/sec	±0.83%	93

iojs 1.8.1

Method	Operations	Accuracy	Sampled	Fastest
BrowserBuffer#bracket-notation	10,990,488 ops/sec	±1.11%	91
Uint8Array#bracket-notation	11,268,757 ops/sec	±0.65%	97
NodeBuffer#bracket-notation	11,353,260 ops/sec	±0.83%	94	✓
BrowserBuffer#concat	378,954 ops/sec	±0.74%	94
Uint8Array#concat	1,358,288 ops/sec	±0.97%	87
NodeBuffer#concat	1,934,050 ops/sec	±1.11%	78	✓
BrowserBuffer#copy(16000)	894,538 ops/sec	±0.56%	84
Uint8Array#copy(16000)	1,442,656 ops/sec	±0.71%	96
NodeBuffer#copy(16000)	1,457,898 ops/sec	±0.53%	92	✓
BrowserBuffer#copy(16)	12,870,457 ops/sec	±0.67%	95
Uint8Array#copy(16)	16,643,989 ops/sec	±0.61%	93	✓
NodeBuffer#copy(16)	14,885,848 ops/sec	±0.74%	94
BrowserBuffer#new(16000)	109,264 ops/sec	±4.21%	63
Uint8Array#new(16000)	138,916 ops/sec	±1.87%	61
NodeBuffer#new(16000)	281,449 ops/sec	±3.58%	51	✓
BrowserBuffer#new(16)	1,362,935 ops/sec	±0.56%	99
Uint8Array#new(16)	6,193,090 ops/sec	±0.64%	95	✓
NodeBuffer#new(16)	4,745,425 ops/sec	±1.56%	90
BrowserBuffer#readDoubleBE	118,127 ops/sec	±0.59%	93	✓
DataView#getFloat64	107,332 ops/sec	±0.65%	91
NodeBuffer#readDoubleBE	116,274 ops/sec	±0.94%	95
BrowserBuffer#readFloatBE	150,326 ops/sec	±0.58%	95	✓
DataView#getFloat32	110,541 ops/sec	±0.57%	98
NodeBuffer#readFloatBE	121,599 ops/sec	±0.60%	87
BrowserBuffer#readUInt32LE	814,147 ops/sec	±0.62%	93
DataView#getUint32	137,592 ops/sec	±0.64%	90
NodeBuffer#readUInt32LE	931,650 ops/sec	±0.71%	96	✓
BrowserBuffer#slice	878,590 ops/sec	±0.68%	93
Uint8Array#subarray	2,843,308 ops/sec	±1.02%	90
NodeBuffer#slice	4,998,316 ops/sec	±0.68%	90	✓
BrowserBuffer#writeFloatBE	65,927 ops/sec	±0.74%	93
DataView#setFloat32	139,823 ops/sec	±0.97%	89	✓
NodeBuffer#writeFloatBE	135,763 ops/sec	±0.65%	96

Testing the project

First, install the project:

npm install

Then, to run tests in Node.js, run:

npm run test-node

To test locally in a browser, you can run:

npm run test-browser-local

This will print out a URL that you can then open in a browser to run the tests, using Zuul.

To run automated browser tests using Saucelabs, ensure that your SAUCE_USERNAME and SAUCE_ACCESS_KEY environment variables are set, then run:

npm test

This is what's run in Travis, to check against various browsers. The list of browsers is kept in the .zuul.yml file.

JavaScript Standard Style

This module uses JavaScript Standard Style.

To test that the code conforms to the style, npm install and run:

./node_modules/.bin/standard

credit

This was originally forked from buffer-browserify.

license

MIT. Copyright (C) Feross Aboukhadijeh, and other contributors. Originally forked from an MIT-licensed module by Romain Beauxis.