detect-indent

What is detect-indent?

The detect-indent npm package is designed to analyze a given piece of text and determine the indentation style used. This can be particularly useful in scenarios where maintaining consistent code formatting is crucial, such as in collaborative coding projects. It can detect both spaces and tabs used for indentation and provide information about the most used indentation type and size.

What are detect-indent's main functionalities?

Detecting indentation from a string

This feature allows you to pass a string of text to the `detectIndent` function, which analyzes the indentation used in the text. It returns an object containing the amount of indentation, the type of indentation (spaces or tabs), and the actual indentation string.

const detectIndent = require('detect-indent');
const code = '  const x = 1;\n  const y = 2;';
const indent = detectIndent(code);
console.log(indent); // {amount: 2, type: 'space', indent: '  '}

Other packages similar to detect-indent

indent-string

The indent-string package is used for adding indentation to strings. While detect-indent is focused on detecting and analyzing indentation, indent-string allows you to modify strings by adding a specified amount of indentation. This makes indent-string complementary to detect-indent, as you could detect indentation with one and apply it with the other.

strip-indent

Strip-indent is designed to remove leading indentation from every line in a string. This is somewhat the inverse of what detect-indent does; while detect-indent identifies the indentation style and level, strip-indent removes it entirely. This can be useful in preprocessing text to normalize indentation before further processing or display.

README

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 detect-indent

Usage

Here we modify a JSON file while persisting the indentation:

import fs from 'node:fs';
import detectIndent from 'detect-indent';

/*
{
    "ilove": "pizza"
}
*/
const file = fs.readFileSync('foo.json', 'utf8');

// Tries to detect the indentation and falls back to a default if it can't
const indent = detectIndent(file).indent || '    ';

const json = JSON.parse(file);

json.ilove = 'unicorns';

fs.writeFileSync('foo.json', JSON.stringify(json, undefined, indent));
/*
{
    "ilove": "unicorns"
}
*/

API

Accepts a string and returns an object with stats about the indentation:

• amount {number} - Amount of indentation, for example 2
• type {'tab' | 'space' | undefined} - Type of indentation. Possible values are 'tab', 'space' or undefined if no indentation is detected
• indent {string} - Actual indentation

Algorithm

The current algorithm looks for the most common difference between two consecutive non-empty lines.

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:

html {
  box-sizing: border-box;
}

body {
  background: gray;
}

p {
    line-height: 1.3em;
    margin-top: 1em;
    text-indent: 2em;
}

Source.

Furthermore, if there are more than one most used difference, the indentation with the most lines is selected.

In the following example, the indentation is detected as 4-spaces:

body {
  background: gray;
}

p {
    line-height: 1.3em;
    margin-top: 1em;
    text-indent: 2em;
}

Related

• detect-indent-cli - CLI for this module
• detect-newline - Detect the dominant newline character of a string
• detect-indent-rs - Rust port

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