filter-object.js

describe('filterObject', function () {
  it('should filter out falsey values', function () {
    var actual = filterObject({
      empty: '',
      depth: 0,
      nested: {
        empty: '',
        depth: 1,
        nested: {
          empty: '',
          str: 'hello',
          depth: 2,
          value: false,
          other: true
        }
      }
    });
    var expected = {
      nested: {
        depth: 1,
        nested: {
          str: 'hello',
          depth: 2,
          other: true
        }
      }
    };

    expect.expect(actual).to.deep.equal(expected);
  });
});

filter-object.spec.js

function filterObject(object, predicate) {
  if (typeof predicate !== 'function') {
    predicate = function(value, key, o) {
      if (!value) {
        delete o[key];
      }
    };
  }
  if (typeof object === 'object') {
    for (var key in object) {
      predicate.call(this, object[key], key, object);
      filterObject(object[key], predicate);
    }
  }
  return object;
}