,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()`
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