Array Reduce

Question 1

What does Array.reduce do?

Answer 1

user-supplied “reducer” callback function on each element of the array, in order, passing in the return value from the calculation on the preceding element.

Question 2

What action should the callback function perform?

Answer 2

A function to execute for each element in the array

Question 3

What should the callback function return?

Answer 3

For the last invocation, the return value becomes the return value of reduce()

Question 4

What is Array.reduce useful for?

Answer 4

method is an iterative method. It runs a “reducer” callback function over all elements in the array, in ascending-index order, and accumulates them into a single value. Every time, the return value of callbackFn is passed into callbackFn again on next invocation as accumulator
simplification of code