find-path-of-nested-child-object-inside-parent-object.js

// starting with: object, childObject

// goal
// - given an object/array and a child object/array, give me the path to the child

// some code copied from: https://github.com/moxystudio/js-deep-for-each

function isPlainObject (obj) {
  return Object.prototype.toString.call(obj) === '[object Object]';
}

function forEachObject(obj, fn, path) {
    for (const key in obj) {
        const deepPath = path ? `${path}.${key}` : key;

        // Note that we always use obj[key] because it might be mutated by forEach
        fn.call(obj, obj[key], key, obj, deepPath);

        deepForEach(obj[key], fn, deepPath);
    }
}

function forEachArray(array, fn, path) {
    array.forEach((value, index, arr) => {
        const deepPath = `${path}[${index}]`;

        fn.call(arr, value, index, arr, deepPath);

        // Note that we use arr[index] because it might be mutated by forEach
        deepForEach(arr[index], fn, deepPath);
    });
}

function deepForEach(value, fn, path) {
    path = path || '';

    if (Array.isArray(value)) {
        forEachArray(value, fn, path);
    } else if (isPlainObject(value)) {
        forEachObject(value, fn, path);
    }
}

function getPathOfChildObject (parentObj, childObj) {
  let path;

  deepForEach(parentObj, function (value, key, subject, currentPath) {
    if (value === childObj) {
      path = currentPath;
    }
  })

  return path;
}