buffer

The Buffer constructor returns instances of Uint8Array that have their prototype changed to Buffer.prototype. Because Buffer is a subclass of Uint8Array, the returned instances possess all both Node Buffer methods and standard Uint8Array methods.

Key behaviors:

• Square bracket notation (e.g., buf[4]) works and returns a single octet.
• The Uint8Array prototype itself remains unmodified.
• The implementation is backed by Typed Arrays (Uint8Array/ArrayBuffer) for high performance.

After installing the project, you can execute the test suite in a Node.js environment using the following command.

npm run test-node

To test the project locally in a browser, use one of the following commands depending on the browser's ES6 support. These commands will provide a URL that you can open in a browser to run tests via airtap.

• For ES5 browsers (no ES6 support): npm run test-browser-old-local
• For ES6 compliant browsers: npm run test-browser-new-local

To use this module directly in your project (without using Browserify), install it via npm:

npm install buffer

If you are not using a bundler at all, you can use the standalone script.

The module's API is designed to be 100% identical to Node.js's Buffer API.

If you are using Browserify, you can simply require('buffer') or use the Buffer global; the module will be automatically included in your bundle.

If you need to depend on this module explicitly (without Browserify), you must use the trailing slash in the require statement to ensure the npm module is used instead of the Node.js core module:

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

This module follows JavaScript Standard Style. To check if the code conforms to this style, install the dependencies and run the standard binary.

npm install
./node_modules/.bin/standard

To run automated browser tests via Saucelabs (the same method used in Travis CI), you must first set your SAUCE_USERNAME and SAUCE_ACCESS_KEY environment variables. Then, run the standard test command.

npm test

To convert an ArrayBuffer to a Buffer, use the Buffer.from method. This operation does not perform a copy, making it very fast.

var buffer = Buffer.from(arrayBuffer)

To convert a Buffer to an ArrayBuffer, you can use the .buffer property (available on all Uint8Array objects). To ensure you get the correct view of the data, you should slice the underlying buffer using the byteOffset and byteLength of the buffer:

var arrayBuffer = buffer.buffer.slice(
  buffer.byteOffset, buffer.byteOffset + buffer.byteLength
)

Use Buffer.alloc(size[, fill[, encoding]]) to create a new Buffer of a specified size and initialize it with fill.

• size: The number of bytes to allocate.
• fill: The value used to fill the buffer. If fill is a string, encoding must be provided.
• encoding: The encoding used if fill is a string.

Use buf.slice(start[, end]) to return a new Buffer that references the same memory as the original, but with a different start and end offset.

• start: The starting index (inclusive).
• end: The ending index (exclusive). If omitted, it defaults to the buffer length.

Warning: The new buffer shares the same underlying memory as the original. Modifying the slice will modify the original buffer.