| # detect-indent [](https://travis-ci.org/sindresorhus/detect-indent) |
| |
| > Detect the indentation of code |
| |
| Pass in a string of any kind of text and get the indentation. |
| |
| |
| ## Use cases |
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| - Persisting the indentation when modifying a file. |
| - Have new content match the existing indentation. |
| - Setting the right indentation in your editor. |
| |
| |
| ## Install |
| |
| ``` |
| $ npm install --save detect-indent |
| ``` |
| |
| |
| ## Usage |
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| Here we modify a JSON file while persisting the indentation: |
| |
| ```js |
| var fs = require('fs'); |
| var detectIndent = require('detect-indent'); |
| |
| /* |
| { |
| "ilove": "pizza" |
| } |
| */ |
| var file = fs.readFileSync('foo.json', 'utf8'); |
| |
| // tries to detect the indentation and falls back to a default if it can't |
| var indent = detectIndent(file).indent || ' '; |
| |
| var json = JSON.parse(file); |
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| json.ilove = 'unicorns'; |
| |
| fs.writeFileSync('foo.json', JSON.stringify(json, null, indent)); |
| /* |
| { |
| "ilove": "unicorns" |
| } |
| */ |
| ``` |
| |
| |
| ## API |
| |
| Accepts a string and returns an object with stats about the indentation: |
| |
| * `amount` {number} - Amount of indentation, e.g. `2` |
| * `type` {string|null} - Type of indentation. Possible values are `tab`, `space` or `null` if no indentation is detected |
| * `indent` {string} - Actual indentation |
| |
| |
| ## 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: |
| |
| ```css |
| html { |
| box-sizing: border-box; |
| } |
| |
| body { |
| background: gray; |
| } |
| |
| p { |
| line-height: 1.3em; |
| margin-top: 1em; |
| text-indent: 2em; |
| } |
| ``` |
| |
| [Source.](https://medium.com/@heatherarthur/detecting-code-indentation-eff3ed0fb56b#3918) |
| |
| 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: |
| |
| ```css |
| body { |
| background: gray; |
| } |
| |
| p { |
| line-height: 1.3em; |
| margin-top: 1em; |
| text-indent: 2em; |
| } |
| ``` |
| |
| |
| ## Related |
| |
| - [detect-indent-cli](https://github.com/sindresorhus/detect-indent-cli) - CLI for this module |
| |
| |
| ## License |
| |
| MIT © [Sindre Sorhus](http://sindresorhus.com) |