Tally the Banana Explainer


Aim of the puzzle: Use the .reduce() array method to count the number of bananas in an array of fruits.
Walk through of solution:
.reduce() is used to calculate a single value from an array, for example, adding all the numbers of an array into a single sum.

.reduce() uses 2 arguments: a callback function, and a starting value. The callback also uses 2 parameters: the total value so far, and the current value.

For example, in the following code:

[1, 2, 3].reduce((total, currentNumber) => {
  return total + currentNumber;
}, 0)
// This returns 6

In this code, .reduce() has a callback function and 0 as a starting value for the callback. The callback function iterates over the array, and adds each element to the total value.

In this puzzle, we want .reduce() to only add to total if currentFruit === 'banana'). If this is true, total will be incremented by 1, and then total is returned. If the currentFruit is not 'banana', total is returned without being incremented, and .reduce() moves on to the next element.

To complete the puzzle, add the test currentFruit === 'banana' to the if statement, then add total++ to the code block. After the if statement, add return total.

Sample code solution:

import { fruits } from 'grasshopper.belafonte';
for (let fruit of fruits) {
let bananaCount = fruits.reduce((total, currentFruit) => {
    if (currentFruit === 'banana') {
    return total;
}, 0);


Javascript Concepts: .reduce(), Arrays, Array Methods, If Statements, Import Declarations, Return Statements, For Of Loops, console.log()