71 lines
1.8 KiB
Markdown
71 lines
1.8 KiB
Markdown
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# isBinaryFile
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Detects if a file is binary in Node.js using ✨promises✨. Similar to [Perl's `-B` switch](http://stackoverflow.com/questions/899206/how-does-perl-know-a-file-is-binary), in that:
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- it reads the first few thousand bytes of a file
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- checks for a `null` byte; if it's found, it's binary
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- flags non-ASCII characters. After a certain number of "weird" characters, the file is flagged as binary
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Much of the logic is pretty much ported from [ag](https://github.com/ggreer/the_silver_searcher).
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Note: if the file doesn't exist or is a directory, an error is thrown.
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## Installation
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```
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npm install isbinaryfile
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```
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## Usage
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Returns `Promise<boolean>` (or just `boolean` for `*Sync`). `true` if the file is binary, `false` otherwise.
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### isBinaryFile(filepath)
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* `filepath` - a `string` indicating the path to the file.
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### isBinaryFile(bytes[, size])
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* `bytes` - a `Buffer` of the file's contents.
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* `size` - an optional `number` indicating the file size.
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### isBinaryFileSync(filepath)
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* `filepath` - a `string` indicating the path to the file.
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### isBinaryFileSync(bytes[, size])
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* `bytes` - a `Buffer` of the file's contents.
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* `size` - an optional `number` indicating the file size.
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### Examples
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Here's an arbitrary usage:
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```javascript
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const isBinaryFile = require("isbinaryfile").isBinaryFile;
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const fs = require("fs");
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const filename = "fixtures/pdf.pdf";
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const data = fs.readFileSync(filename);
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const stat = fs.lstatSync(filename);
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isBinaryFile(data, stat.size).then((result) => {
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if (result) {
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console.log("It is binary!")
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}
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else {
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console.log("No it is not.")
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}
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});
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const isBinaryFileSync = require("isbinaryfile").isBinaryFileSync;
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const bytes = fs.readFileSync(filename);
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const size = fs.lstatSync(filename).size;
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console.log(isBinaryFileSync(bytes, size)); // true or false
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```
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## Testing
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Run `npm install`, then run `npm test`.
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