WGU D280A - ITSW 3151 JavaScript Programming - Comprehensive FA Guide 2024.

D280A ITSW 3151



JavaScript
Programming

COMPREHENSIVE FA GUIDE



2024

,1. Which of the following methods will concatenate arrays without altering
the original arrays?

- A. `Array.prototype.push()`

- B. `Array.prototype.concat()`
- C. `Array.prototype.splice()`

- D. `Array.prototype.unshift()`


Answer: B. Array.prototype.concat()



Rationale: `concat()` method returns a new array, combining elements
from the original arrays without modifying them.



2. What is the output of the following code snippet?
```javascript

const obj = { a: 1, b: 2, c: 3 };

const { a, ...rest } = obj;

console.log(rest);
```
- A. `{ b: 2, c: 3 }`

- B. `{ a: 1, b: 2 }`
- C. `{ c: 3 }`

- D. `undefined`

, Answer: A. { b: 2, c: 3 }



Rationale: Using the rest operator (`...rest`), the code collects the
remaining properties into a new object `rest` after destructuring `a`.



3. In JavaScript, which call is made as soon as a Promise object is created?
- A. `Promise.prototype.then()`

- B. `Promise.prototype.catch()`

- C. `Promise.prototype.finally()`
- D. The executor function passed to the `Promise` constructor



Answer: D. The executor function passed to the Promise constructor



Rationale: When a Promise is created, the executor function is
immediately executed.



4. Which array method is used to iterate over all elements of an array and
returns a single accumulated result?
- A. `Array.prototype.filter()`

- B. `Array.prototype.forEach()`

- C. `Array.prototype.reduce()`

- D. `Array.prototype.map()`