detect-indent

detect-indent

Detect the indentation of code

Pass in a string of any kind of text and get the indentation.

Use cases

• 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

// modify a JSON file while persisting the indentation in Node
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);

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} the amount of indentation, e.g. 2
• type: {String|Null} the type of indentation. Possible values are tab, space or null if no indentation is detected
• indent: {String} the actual indentation

CLI

$ npm install --global detect-indent

$ detect-indent --help

  Usage
    detect-indent <file>
    echo <string> | detect-indent

  Example
    echo '  foo\n  bar' | detect-indent | wc --chars
    2

Algorithm

It first strips off multi-line comments. Then goes through each line counting whether it's tabs or spaces and the indent size coerced to an even number. The resulting indent size is the GCD (Greates Common Divisor) of the gathered line indent sizes and the type is the most used type.

License

MIT © Sindre Sorhus