121 lines
2.4 KiB
Markdown
121 lines
2.4 KiB
Markdown
# detect-indent [](https://travis-ci.org/sindresorhus/detect-indent)
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> Detect the indentation of code
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Pass in a string of any kind of text and get the indentation.
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## Use cases
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- Persisting the indentation when modifying a file.
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- Have new content match the existing indentation.
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- Setting the right indentation in your editor.
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## Install
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```sh
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$ npm install --save detect-indent
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```
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## Usage
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```js
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// modify a JSON file while persisting the indentation in Node
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var fs = require('fs');
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var detectIndent = require('detect-indent');
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/*
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{
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"ilove": "pizza"
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}
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*/
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var file = fs.readFileSync('foo.json', 'utf8');
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// tries to detect the indentation and falls back to a default if it can't
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var indent = detectIndent(file).indent || ' ';
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var json = JSON.parse(file);
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json.ilove = 'unicorns';
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fs.writeFileSync('foo.json', JSON.stringify(json, null, indent));
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/*
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{
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"ilove": "unicorns"
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}
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*/
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```
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## API
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Accepts a string and returns an object with stats about the indentation:
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* `amount`: {Number} the amount of indentation, e.g. `2`
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* `type`: {String|Null} the type of indentation. Possible values are `tab`, `space` or `null` if no indentation is detected
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* `indent`: {String} the actual indentation
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## CLI
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```sh
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$ npm install --global detect-indent
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```
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```
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$ detect-indent --help
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Usage
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detect-indent <file>
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echo <string> | detect-indent
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Example
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echo ' foo\n bar' | detect-indent | wc --chars
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2
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```
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## Algorithm
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The current algorithm looks for the most common difference between two consecutive non-empty lines.
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In the following example, even if the 4-space indentation is used 3 times whereas the 2-space one is used 2 times, it is detected as less used because there were only 2 differences with this value instead of 4 for the 2-space indentation:
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```css
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html {
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box-sizing: border-box;
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}
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body {
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background: grey;
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}
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p {
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line-height: 1.3em;
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margin-top: 1em;
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text-indent: 2em;
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}
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```
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[Source](https://medium.com/@heatherarthur/detecting-code-indentation-eff3ed0fb56b#3918).
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Furthermore, if there are more than one most used difference, the indentation with the most lines is selected.
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In the following example, the indentation is detected as 4-spaces:
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```css
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body {
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background: grey;
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}
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p {
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line-height: 1.3em;
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margin-top: 1em;
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text-indent: 2em;
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}
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```
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## License
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MIT © [Sindre Sorhus](http://sindresorhus.com)
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