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Detect the indentation of code

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

• Persisting the indentation when modifying a file.
• Have new content match the existing indentation.
• Setting the right indentation in your editor.

npm install detect-indent

Here we modify a JSON file while persisting the indentation:

importfsfrom'node:fs';importdetectIndentfrom'detect-indent';/*{    "ilove": "pizza"}*/constfile=fs.readFileSync('foo.json','utf8');// Tries to detect the indentation and falls back to a default if it can'tconstindent=detectIndent(file).indent||'    ';constjson=JSON.parse(file);json.ilove='unicorns';fs.writeFileSync('foo.json',JSON.stringify(json,undefined,indent));/*{    "ilove": "unicorns"}*/

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

• type {'tab' | 'space' | undefined} - The type of indentation. It isundefined if no indentation is detected.
• amount {number} - The amount of indentation. For example,2.
• indent {string} - The actual indentation.

The current algorithm looks for the most common difference between two consecutive non-empty lines. Single-space indentations and changes are ignored by default to prevent common false positives from comment alignment.

In the following example, even if 4-space indentation appears 3 times while 2-space appears only 2 times, the 2-space indentation is detected because there are 4 indent changes of 2 spaces vs only 2 changes of 4 spaces:

html {box-sizing: border-box;}body {background: gray;}p {line-height:1.3em;margin-top:1em;text-indent:2em;}

Source.

Furthermore, if there are multiple indent differences with the same usage count, 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;}

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