Recurse JavaScript Object from Path

recurse_obj.js

/**
 * Recursive function to walk down into the config object and return the requested data
 * 
 * @param {string[]} pathArray Array containing the paths to the requested key
 * @param {Object} inputObj The object being traversed. 
 * @param {number} [idx=0] Current index. Used internally to determine where in the pathArray we are
 * 
 * @returns {any|null} Requested config setting(s)
*/
const recurseConfigPath = (pathArray, inputObj, idx = 0) => {
  // For each level of the array, get the next path
  let output;
  const currPath = pathArray[idx];

  // Push this object into the output
  output = inputObj[currPath];

  if (typeof pathArray[++idx] !== 'undefined') {
    // The path goes deeper, recurse into the next index
    output = recurseConfigPath(pathArray, inputObj[currPath], idx);
  }

  return output ?? null;
}

// Usage:
const configObj = {
  root: {
    child: {
      data: 'string'
    }
  }
};

const path = ['root', 'child', 'data'];

const data = recurseConfigPath(path, configObj);

console.log(data); // 'string'

// Can also do arrays, if index is known:
const configObj = {
  root: {
    child: [
      'string'
    ]
  }
};

const path = ['root', 'child', 0];

const data = recurseConfigPath(path, configObj);

console.log(data); // 'string'