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.

Node.js Series Overview

  1. String Replace All Appearances
  2. Remove All Whitespace From a String in JavaScript
  3. Generate a Random ID or String in Node.js or JavaScript
  4. Remove Extra Spaces From a String in JavaScript or Node.js
  5. Remove Numbers From a String in JavaScript or Node.js
  6. Get the Part Before a Character in a String in JavaScript or Node.js
  7. Get the Part After a Character in a String in JavaScript or Node.js
  8. How to Check if a Value is a String in JavaScript or Node.js
  9. Check If a String Includes All Strings in JavaScript/Node.js/TypeScript
  10. Check if a Value is a String in JavaScript and Node.js
  11. Limit and Truncate a String to a Given Length in JavaScript and Node.js
  12. Split a String into a List of Characters in JavaScript and Node.js
  13. How to Generage a UUID in Node.js
  14. Reverse a String in JavaScript or Node.js
  15. Split a String into a List of Lines in JavaScript or Node.js
  16. Split a String into a List of Words in JavaScript or Node.js
  17. Detect if a String is in camelCase Format in Javascript or Node.js
  18. Check If a String Is in Lowercase in JavaScript or Node.js
  19. Check If a String is in Uppercase in JavaScript or Node.js
  20. Get the Part After First Occurrence in a String in JavaScript or Node.js
  21. Get the Part Before First Occurrence in a String in JavaScript or Node.js
  22. Get the Part Before Last Occurrence in a String in JavaScript or Node.js
  23. Get the Part After Last Occurrence in a String in JavaScript or Node.js
  24. How to Count Words in a File
  25. How to Shuffle the Characters of a String in JavaScript or Node.js
  26. Append Characters or Words to a String in JavaScript or Node.js (Coming soon)
  27. Check if a String is Empty in JavaScript or Node.js (Coming soon)
  28. Ensure a String Ends with a Given Character in JavaScript or Node.js (Coming soon)
  29. Left-Trim Characters Off a String in JavaScript or Node.js (Coming soon)
  30. Right-Trim Characters Off a String in JavaScript or Node.js (Coming soon)
  31. Lowercase the First Character of a String in JavaScript or Node.js (Coming soon)
  32. Uppercase the First Character of a String in JavaScript or Node.js (Coming soon)
  33. Prepend Characters or Words to a String in JavaScript or Node.js (Coming soon)
  1. Get Number of Seconds Since Epoch in JavaScript
  2. Get Tomorrow’s Date in JavaScript
  3. Increase a Date in JavaScript by One Week
  4. Add Seconds to a Date in Node.js and JavaScript
  5. Add Month(s) to a Date in JavaScript or Node.js
  6. Add Week(s) to a Date in JavaScript or Node.js
  7. Get the Current Year in JavaScript or Node.js
  8. How to Get a UNIX Timestamp in JavaScript or Node.js
  9. How to Convert a UNIX Timestamp to a Date in JavaScript or Node.js
  10. Add Days to a Date in JavaScript or Node.js
  11. Get Yesterday's Date in JavaScript or Node.js
  12. Add Minutes to a Date in JavaScript or Node.js (Coming soon)
  13. Add Hours to a Date in JavaScript or Node.js (Coming soon)
  14. Check If a Date Is Today in JavaScript or Node.js (Coming soon)
  15. Check If a Date is Tomorrow in JavaScript or Node.js (Coming soon)
  16. Check If a Date is Yesterday in JavaScript or Node.js (Coming soon)
  17. How to Format a Date YYYY-MM-DD in JavaScript or Node.js (Coming soon)

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

Explore the Library

Find interesting tutorials and solutions for your problems.