freeCodeCamp Challenge Guide: Test if a Value is of a Specific Data Structure Type

Test if a Value is of a Specific Data Structure Type

Problem Explanation

To begin, locate the file “tests/1_unit_tests.js” and scroll to the suite of tests for ‘Objects’.

This file contains multiple suites of tests for the project, and this challenge requires you to make the tests in /** 17 */ pass.


Hint 1

The challenge uses objects defined above the tests. Look closely at both, and determine whether the object or its properties will have the type being compared against in the assertion.

Hint 2

Check the error messages to determine if your understanding of the object or property’s type was correct.

Hint 3

The lines in the test should be changed from to either assert.typeOf() or assert.notTypeOf().


Solution 1 (Click to Show/Hide)
test('#typeof, #notTypeOf', function() {
  /** 17 #typeOf asserts that value’s type is the given string, **/
  // as determined by Object.prototype.toString.
  // Use #typeOf or #notTypeOf where appropriate
  assert.typeOf(myCar, 'object');
  assert.typeOf(myCar.model, 'string');
  assert.notTypeOf(airlinePlane.wings, 'string');
  assert.typeOf(airlinePlane.engines, 'array');
  assert.typeOf(myCar.wheels, 'number');