Implement a camelCaseKeys function

Apr 01, 2024

camelCase is a convention used in programming and naming conventions where multiple words are combined into one continuous string of text, with each word within the string capitalized except for the first word.

camelCase conventions are followed in JavaScript codebases as well. We need to implement a camelCaseKeys functon that can convert all keys in object to follow camelCase convention.

1. Basic implementation

Input can have nested objects or array of objects. Try not to mutate the original input.

import camelCase from './src/utils.js';

function camelCaseKeys(input) {
  // for arrays
  if (Array.isArray(input)) {
    const outArr = [];
    input.forEach((item) => {
      outArr.push(camelCaseKeys(item));
    });
    return outArr;
  }

  // for objects
  const outObj = Object.create({});

  for (const key in input) {
    // avoid iterating over inherited keys
    if (Object.hasOwn(input, key)) {
      const value = input[key];

      if (typeof value !== 'object') {
        outObj[camelCase(key)] = value;
      } else {
        outObj[camelCase(key)] = camelCaseKeys(value);
      }
    }
  }
  return outObj;
}

// Usage

const convertedObj = camelCaseKeys({
  hello_world: true,
  hello: {
    baz_bar: [{ name: 'JS', age_in_years: 24 }]
  }
});

console.log(convertedObj);

/**
 * Yields
 * {
    "helloWorld": true,
    "hello": {
        "bazBar": [
            {
                "name": "JS",
                "ageInYears": 24
            }
        ]
    }
}
 */

Here the implementation of camelCase is not really important. You can use any technique solution you prefer present on the internet. The goal is not to focus on utility but rather the recursion done.