istextorbinary - 检查一个文件是否文本或二进制。

Node.js 文件系统

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详细介绍

Is Text or Binary?

Determine if a filename and/or buffer is text or binary. Smarter detection than the other solutions.

Determination works like so:

Extension Check: If filename is available, check if any of its extensions (from right to left) are an text extension or a binary extension, this is near instant.
Contents Check: If no filename was provided, or the extension check was indeterminate, then check the contents of the buffer.

The extension check will check each of the filename's extensions, from right to left. This is done as certain applications utilise multiple extensions for transformations, such as app.x.y may tell a compiler to transform from x format to y format, in this case perhaps x is not a recognized extension but y is, in which case we can make use of that to provide superior accuracy and convenience compared to just checking the rightmost extension.

The contents check (with the default options) will check 24 bytes at the start, middle, and end of the buffer. History has shown that checking all three locations is mandatory for accuracy, and that anything less is not accurate. This technique offers superior performance while still offering superior accuracy. Alternatives generally just do 1000 bytes at the start, which is slower, and inaccurate.

One cannot just do the contents check alone because UTF16 characters are indistinguishable from binary which would return an inaccurate result, hence why the combination is necessary for accuracy, with performance for known extensions a side-effect.

As such, this library's combination of extension check (if filename is provided), then contents check (if buffer is provided), offers superior performance and accuracy to alternatives.

Ever since 2012, this module's superior accuracy and performance has been essential to the operation of DocPad and its other dependents.

Usage

Complete API Documentation.

const { isText, isBinary, getEncoding } = require('istextorbinary')

isText(aFilename) // returns true if a text file otherwise false, checks only filename
isText(null, aBuffer) // returns true if a text file otherwise false, checks only buffer
isText(aFilename, aBuffer) // returns true if a text file otherwise false, checks filename then buffer
isText(null, null) // returns null

isBinary(aFilename) // returns true if a binary file otherwise false, checks only filename
isBinary(null, aBuffer) // returns true if a binary file otherwise false, checks only buffer
isBinary(aFilename, aBuffer) // returns true if a binary file otherwise false, checks filename then buffer
isBinary(null, null) // returns null

getEncoding(aBuffer) // returns 'binary' if it contained non-utf8 characters, otherwise returns 'utf8'

Install

npm

Install: npm install --save istextorbinary
Import: import * as pkg from ('istextorbinary')
Require: const pkg = require('istextorbinary')

jspm

<script type="module">
    import * as pkg from '//dev.jspm.io/istextorbinary@4.3.0'
</script>

Editions

This package is published with the following editions:

istextorbinary aliases istextorbinary/source/index.js
istextorbinary/source/index.js is ESNext source code for Node.js with Require for modules
istextorbinary/edition-browsers/index.js is ESNext compiled for web browsers with Require for modules

TypeScript

This project provides its type information via inline JSDoc Comments. To make use of this in TypeScript, set your maxNodeModuleJsDepth compiler option to 5 or thereabouts. You can accomlish this via your tsconfig.json file like so:

{
  "compilerOptions": {
    "maxNodeModuleJsDepth": 5
  }
}

History

Discover the release history by heading on over to the HISTORY.md file.

Contribute

Discover how you can contribute by heading on over to the CONTRIBUTING.md file.

Backers

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Contributors

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