Online Access Free JS-Dev-101 Practice Test

Refer to the code below:
let inArray = [ [1, 2], [3, 4, 5] ];
Which two statements result in the array [1, 2, 3, 4, 5]?
(With corrected typing errors: usArray → inArray, .. → ....)

• A.[].concat(...inArray);
• B.[].concat.apply(inArray, []);
• C.[].concat.apply({}, inArray);
• D.[].concat::...inArray();

Considering type coercion, what does the following expression evaluate to?
true + '13' + NaN

• A.'true13'
• B.'113NaN'
• C.'true13NaN'
• D.14

Refer to the code below:
01 let o = {
02 get js() {
03 let city1 = String('St. Louis');
04 let city2 = String('New York');
05
06 return {
07 firstCity: city1.toLowerCase(),
08 secondCity: city2.toLowerCase(),
09 }
10 }
11 }
What value can a developer expect when referencing o.js.secondCity?

• A.undefined
• B.An error
• C.'new york'
• D.'New York'

Refer to the following array:
let arr = [1, 2, 3, 4, 5];
Which two lines of code result in a second array, arr2, created such that arr2 is a reference to arr?

• A.let arr2 = arr;
• B.let arr2 = arr.sort();
• C.let arr2 = arr.slice(0, 5);
• D.let arr2 = Array.from(arr);

A developer removes the HTML class attribute from the checkout button, so now it is simply:
<button>Checkout</button>
There is a test to verify the existence of the checkout button, however it looks for a button with class="blue". The test fails because no such button is found.
Which type of test category describes this test?

• A.True negative
• B.False negative
• C.False positive
• D.True positive