236 lines
6.6 KiB
Markdown
236 lines
6.6 KiB
Markdown
# uint8arrays
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[](https://codecov.io/gh/achingbrain/uint8arrays)
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[](https://github.com/achingbrain/uint8arrays/actions/workflows/js-test-and-release.yml?query=branch%3Amain)
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> Utility functions to make dealing with Uint8Arrays easier
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# About
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<!--
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!IMPORTANT!
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Everything in this README between "# About" and "# Install" is automatically
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generated and will be overwritten the next time the doc generator is run.
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To make changes to this section, please update the @packageDocumentation section
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of src/index.js or src/index.ts
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To experiment with formatting, please run "npm run docs" from the root of this
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repo and examine the changes made.
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-->
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`Uint8Array`s bring memory-efficient(ish) byte handling to browsers - they are similar to Node.js `Buffer`s but lack a lot of the utility methods present on that class.
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This module exports a number of function that let you do common operations - joining Uint8Arrays together, seeing if they have the same contents etc.
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Since Node.js `Buffer`s are also `Uint8Array`s, it falls back to `Buffer` internally where it makes sense for performance reasons.
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## alloc(size)
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Create a new `Uint8Array`. When running under Node.js, `Buffer` will be used in preference to `Uint8Array`.
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## Example
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```ts
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import { alloc } from 'uint8arrays/alloc'
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const buf = alloc(100)
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```
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## allocUnsafe(size)
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Create a new `Uint8Array`. When running under Node.js, `Buffer` will be used in preference to `Uint8Array`.
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On platforms that support it, memory referenced by the returned `Uint8Array` will not be initialized.
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## Example
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```ts
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import { allocUnsafe } from 'uint8arrays/alloc'
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const buf = allocUnsafe(100)
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```
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## compare(a, b)
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Compare two `Uint8Arrays`
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## Example
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```ts
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import { compare } from 'uint8arrays/compare'
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const arrays = [
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Uint8Array.from([3, 4, 5]),
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Uint8Array.from([0, 1, 2])
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]
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const sorted = arrays.sort(compare)
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console.info(sorted)
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// [
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// Uint8Array[0, 1, 2]
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// Uint8Array[3, 4, 5]
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// ]
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```
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## concat(arrays, \[length])
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Concatenate one or more `Uint8Array`s and return a `Uint8Array` with their contents.
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If you know the length of the arrays, pass it as a second parameter, otherwise it will be calculated by traversing the list of arrays.
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## Example
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```ts
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import { concat } from 'uint8arrays/concat'
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const arrays = [
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Uint8Array.from([0, 1, 2]),
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Uint8Array.from([3, 4, 5])
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]
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const all = concat(arrays, 6)
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console.info(all)
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// Uint8Array[0, 1, 2, 3, 4, 5]
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```
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## equals(a, b)
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Returns true if the two arrays are the same array or if they have the same length and contents.
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## Example
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```ts
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import { equals } from 'uint8arrays/equals'
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const a = Uint8Array.from([0, 1, 2])
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const b = Uint8Array.from([3, 4, 5])
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const c = Uint8Array.from([0, 1, 2])
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console.info(equals(a, b)) // false
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console.info(equals(a, c)) // true
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console.info(equals(a, a)) // true
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```
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## fromString(string, encoding = 'utf8')
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Returns a new `Uint8Array` created from the passed string and interpreted as the passed encoding.
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Supports `utf8` and any of the [multibase encodings](https://github.com/multiformats/multibase/blob/master/multibase.csv) as implemented by the [multiformats module](https://www.npmjs.com/package/multiformats).
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## Example
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```ts
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import { fromString } from 'uint8arrays/from-string'
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console.info(fromString('hello world')) // Uint8Array[104, 101 ...
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console.info(fromString('00010203aabbcc', 'base16')) // Uint8Array[0, 1 ...
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console.info(fromString('AAECA6q7zA', 'base64')) // Uint8Array[0, 1 ...
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console.info(fromString('01234', 'ascii')) // Uint8Array[48, 49 ...
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```
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## toString(array, encoding = 'utf8')
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Returns a string created from the passed `Uint8Array` in the passed encoding.
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Supports `utf8` and any of the [multibase encodings](https://github.com/multiformats/multibase/blob/master/multibase.csv) as implemented by the [multiformats module](https://www.npmjs.com/package/multiformats).
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## Example
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```ts
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import { toString } from 'uint8arrays/to-string'
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console.info(toString(Uint8Array.from([104, 101...]))) // 'hello world'
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console.info(toString(Uint8Array.from([0, 1, 2...]), 'base16')) // '00010203aabbcc'
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console.info(toString(Uint8Array.from([0, 1, 2...]), 'base64')) // 'AAECA6q7zA'
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console.info(toString(Uint8Array.from([48, 49, 50...]), 'ascii')) // '01234'
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```
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## withArrayBuffer(buf)
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`Uint8Array`s can be backed by an `ArrayBuffer` or a `SharedArrayBuffer`.
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The types of these two values have diverged in `typescript@5.7` or later.
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Some APIs require `Uint8Array`s backed by `ArrayBuffer`s specifically so call
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`withArrayBuffer` to ensure your `Uint8Array`s are backed the correct type.
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## Example
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```ts
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import { withArrayBuffer } from 'uint8arrays/with-array-buffer'
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const buf = new SharedArrayBuffer(10)
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const arr = new Uint8Array(buf, 0, buf.byteLength)
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const arr2 = withArrayBuffer(arr)
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console.info(arr.buffer.constructor) // [Function: SharedArrayBuffer]
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console.info(arr2.buffer.constructor) // [Function: ArrayBuffer]
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```
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## xor(a, b)
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Returns a `Uint8Array` containing `a` and `b` xored together.
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## Example
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```ts
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import { xor } from 'uint8arrays/xor'
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console.info(xor(Uint8Array.from([1, 0]), Uint8Array.from([0, 1]))) // Uint8Array[1, 1]
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```
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## xorCompare(a, b)
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Compares the distances between two xor `Uint8Array`s.
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## Example
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```ts
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import { xor } from 'uint8arrays/xor'
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import { xorCompare } from 'uint8arrays/xor-compare'
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const target = Uint8Array.from([1, 1])
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const val1 = Uint8Array.from([1, 0])
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const xor1 = xor(target, val1)
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const val2 = Uint8Array.from([0, 1])
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const xor2 = xor(target, val2)
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console.info(xorCompare(xor1, xor2)) // -1 or 0 or 1
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```
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# Install
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```console
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$ npm i uint8arrays
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```
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## Browser `<script>` tag
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Loading this module through a script tag will make its exports available as `Uint8arrays` in the global namespace.
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```html
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<script src="https://unpkg.com/uint8arrays/dist/index.min.js"></script>
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```
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# API Docs
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- <https://achingbrain.github.io/uint8arrays>
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# License
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Licensed under either of
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- Apache 2.0, ([LICENSE-APACHE](https://github.com/achingbrain/uint8arrays/LICENSE-APACHE) / <http://www.apache.org/licenses/LICENSE-2.0>)
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- MIT ([LICENSE-MIT](https://github.com/achingbrain/uint8arrays/LICENSE-MIT) / <http://opensource.org/licenses/MIT>)
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# Contribution
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Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
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