Salesforce JavaScript Developer Practice Exam

What will the console display when the reduce method is used on the array [1, 4, 9, 16] with addition?

1. 30

2. 20

3. 10

4. 40

The correct answer is: 30

When using the reduce method on the array [1, 4, 9, 16] with addition, the console will display 30. The reduce method processes each element of the array and accumulates a single result based on the provided function. In this case, the operation specified is addition. The reduce method begins with the first element of the array as the initial accumulator value, and then adds each subsequent element to this accumulator. Here’s how that works step-by-step: 1. **Initial value**: The first element, 1, is taken as the starting point (the accumulator). 2. **Addition of next element**: The next element, 4, is added to the accumulator: 1 + 4 = 5. 3. **Continue accumulating**: The next element, 9, is added to the current accumulator: 5 + 9 = 14. 4. **Final addition**: Finally, the last element, 16, is added: 14 + 16 = 30. So, the final result after processing all elements is 30, which is why this is the correct answer.