Salesforce JavaScript Developer Practice Exam

What will the output be when slicing the array [1, 4, 9, 16] from index 1 to 3?

1. [9, 16]

2. [4, 9]

3. [1, 4]

4. 4

The correct answer is: [4, 9]

When slicing the array [1, 4, 9, 16] from index 1 to 3, the output will indeed be [4, 9]. In JavaScript, the slice method is used to extract a portion of an array and returns a new array without modifying the original one. The slice method accepts two parameters: the start index and the end index. The start index is inclusive — meaning it will include the element at that index in the output — while the end index is exclusive, meaning it will not include the element at that index. In this case, the slicing starts at index 1, which corresponds to the value 4 in the array. It then goes up to but does not include index 3, which corresponds to the value 16. Therefore, the resulting array includes the elements at indices 1 and 2, which are 4 and 9, respectively, leading to the output of [4, 9]. This understanding of how the slice method works is fundamental for manipulating arrays in JavaScript effectively.