$ npm i get-value-safely

const get = require('get-value-safely');

// Test object.
const obj = {
  c: {
    a: 2,
    b: {
      c: [1, 2, 3, {a: 15, b: 10}, 15]
    },
    c: undefined,
    d: null
  },
  d: ''
};

get(null, 'c.a', 'fallback');

get(obj, 'c.d', 'fallback');

get(obj, 'c.c', 'fallback', true);

get(obj, 'c.b.c.2');

get(obj, 'c.b.c.3.a');

// Same test object.

assert('Test that null object returns fallback', 'fallback' === get(null, 'c.d.d', 'fallback'));

assert('Test that null path returns fallback', 'fallback' === get(obj, null, 'fallback'));

assert('Test that null object and path returns fallback', 'fallback' === get(null, null, 'fallback'));

assert('Test that non existing property returns fallback', 'fallback' === get(obj, 'c.d.d', 'fallback'));

assert('Test that a null falsy property value is well returned', null === get(obj, 'c.d', 'fallback'));

assert('Test that a undefined falsy property value is well returned', undefined === get(obj, 'c.c', 'fallback'));

assert('Test that fallback is returned when falsy flag is activated', 'fallback' === get(obj, 'c.c', 'fallback', true));

assert('Test that an array property returns the well the array', obj.c.b.c === get(obj, 'c.b.c', 'fallback'));

assert('Test that array index value is well returned', 3 === get(obj, 'c.b.c.2', 'fallback'));

assert('Test that fallback is returns when index does not exist', 'fallback' === get(obj, 'c.b.c.10', 'fallback'));

assert('Test that undefined is returned when index and fallback does not exist', undefined === get(obj, 'c.b.c.10'));

assert('Test that nested object inside array can be accesed by array index', 15 === get(obj, 'c.b.c.3.a'));

assert('Test that array length property can be accessed', 5 === get(obj, 'c.b.c.length', 'fallback'));

assert('Test that fallback is not split in reduce, by index', 'fallback' === get(obj, 'c.z.1', 'fallback'));

assert('Test that fallback is not split in reduce, also for falsy', 'fallback' === get(obj, 'c.z.1', 'fallback', true));