---
id: 587d824e367417b2b2512c56
title: Test if a Value is of a Specific Data Structure Type
challengeType: 2
forumTopicId: 301601
dashedName: test-if-a-value-is-of-a-specific-data-structure-type
---

# --description--

As a reminder, this project is being built upon the following starter project cloned from <a href="https://github.com/freeCodeCamp/boilerplate-mochachai/" target="_blank" rel="noopener noreferrer nofollow">GitHub</a>.

`#typeOf` asserts that value's type is the given string, as determined by `Object.prototype.toString`.

# --instructions--

Within `tests/1_unit-tests.js` under the test labeled `#17` in the `Objects` suite, change each `assert` to either `assert.typeOf` or `assert.notTypeOf` to make the test pass (should evaluate to `true`). Do not alter the arguments passed to the asserts.

# --hints--

All tests should pass.

```js
const response = await fetch(code + '/_api/get-tests?type=unit&n=16');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(data.state, 'passed');
```

You should choose the correct method for the first assertion - `typeOf` vs. `notTypeOf`.

```js
const response = await fetch(code + '/_api/get-tests?type=unit&n=16');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[0].method,
  'typeOf',
  'myCar is typeOf Object'
);
```

You should choose the correct method for the second assertion - `typeOf` vs. `notTypeOf`.

```js
const response = await fetch(code + '/_api/get-tests?type=unit&n=16');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[1].method,
  'typeOf',
  'Car.model is a String'
);
```

You should choose the correct method for the third assertion - `typeOf` vs. `notTypeOf`.

```js
const response = await fetch(code + '/_api/get-tests?type=unit&n=16');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[2].method,
  'notTypeOf',
  'Plane.wings is a Number (not a String)'
);
```

You should choose the correct method for the fourth assertion - `typeOf` vs. `notTypeOf`.

```js
const response = await fetch(code + '/_api/get-tests?type=unit&n=16');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[3].method,
  'typeOf',
  'Plane.engines is an Array'
);
```

You should choose the correct method for the fifth assertion - `typeOf` vs. `notTypeOf`.

```js
const response = await fetch(code + '/_api/get-tests?type=unit&n=16');
if (!response.ok) {
  throw Error(await response.text());
}
const data = await response.json();
assert.equal(
  data.assertions[4].method,
  'typeOf',
  'Car.wheels is a Number'
);
```

