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  3. How to Snake_Case Keys of an Object in JavaScript or Node.js

How to Snake_Case Keys of an Object in JavaScript or Node.js

When interacting with data you may run into challenges related to code formatting. Your linter may warn about misalignments from returned objects of third-party libraries or data from APIs.

You’re not in control of the data format and style. And yet you want to comply with your project’s coding style by transforming the data to your preference.

This tutorial shows you how to transform the keys of an object into snake_case format.

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Snake_Case All Keys of a JavaScript Object

In case you prefer snake_case formatting your code you may need to reformat objects you're not in control of.

The following code snippet shows a snake_case_keys function transforming all top-level object keys from their current format to snake_case:

const Str = require('@supercharge/strings')

/**
 * Translate all top-level keys of the given `object` to snake_case.
 *
 * @param {Object} object
 *
 * @returns {Object}
 */
function snake_case_keys (object) {  
  return Object
    .entries(object)
    .reduce((carry, [key, value]) => {
      carry[Str(key).snake().get()] = value

      return carry
    }, {})
}

Modern browsers and Node.js support the Object.entries() method returning an array of the object’s key-value pairs. You can iterate through the returned list of key-value pairs using Array#reduce() to create a new object following your preferred coding style.

Here’s an example showing you the result of transforming an object’s top-level keys to the snake_case format:

const fileImport = {  
  File_Location: '/user/marcus/downloads/data_import.xlsx',
  Created_At: 1610685464300,
  Nested: {
    // the `snake_case_keys` function does not touch nested objects
  }
}

const snake_cased_file_import = snake_case_keys(fileImport)  
// {
//   file_location: '/user/marcus/downloads/data_import.xlsx',
//   created_at: 1610685464300,
//   nested: { … // not touched } 
// }

About the @supercharge/strings Package

I’m the maintainer of the @supercharge/strings package providing convenient string utilities. This package comes in handy when transforming a given string value to snake_case because it removes all special characters like whitespaces, dashes, exclamation marks, and so on:

const Str = require('@supercharge/strings')

const snake_cased = Str('Hello Marcus').snake().get()  
// 'hello_marcus'

Enjoy!

Mentioned Resources

Marcus Pöhls

Marcus is a fullstack JS developer. He’s passionate about the hapi framework for Node.js and loves to build web apps and APIs. Creator of Futureflix and the “learn hapi” learning path.

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