Example

import guessJsonIndent from 'guess-json-indent'

const input = [{ example: true }]
guessJsonIndent(JSON.stringify(input)) // undefined
guessJsonIndent(JSON.stringify(input, undefined, 1)) // 1
guessJsonIndent(JSON.stringify(input, undefined, 2)) // 2
guessJsonIndent(JSON.stringify(input, undefined, 4)) // 4
guessJsonIndent(JSON.stringify(input, undefined, '\t')) // '\t'
guessJsonIndent(JSON.stringify(input, undefined, '\t\t')) // '\t\t'

// Keep the indentation of a JSON string when parsing/serializing it
const jsonString = JSON.stringify(input, undefined, 2)
const indent = guessJsonIndent(jsonString)
const parsedValue = JSON.parse(jsonString)
console.log(JSON.stringify(input, undefined, indent)) // Same as jsonString

Install

npm install guess-json-indent

This package is an ES module and must be loaded using an import or import() statement, not require().

API

guessJsonIndent(jsonString)

The return value is the same as the third argument to JSON.stringify():

undefined: none
integer: number of spaces
string: tabs

Benchmarks

This library is very fast thanks to:

Looking only at the first indented line, which is sufficient in the vast majority of real-life cases
Being specific to JSON

The following benchmarks compares it:

With detect-indent, detect-json-indent and detect-indentation
On a big JSON string (8MB)

guess-json-indent:         43ns
detect-json-indent:  60114470ns
detect-indentation: 141975495ns
detect-indent:      198161087ns

truncate-json: Truncate a JSON string
is-json-value: Check if a value is valid JSON
safe-json-value: ⛑️ JSON serialization should never fail

Support

For any question, don't hesitate to submit an issue on GitHub.

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Contributing

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guess-json-indent

Package Exports

Readme