popcorn.js

/* Popular Ice Cream Totals Quiz
 *
 * Using the data array and .reduce():
 *   - return an object where each property is the name of an ice cream flavor and
 *     each value is an integer that's the total count of that flavor
 *   - store the returned data in a new iceCreamTotals variable
 *
 * Note:
 *   - do not delete the data variable
 *   - do not alter any of the data content
 */

 const data = [
     { name: 'Tyler', favoriteIceCreams: ['Strawberry', 'Vanilla', 'Chocolate', 'Cookies & Cream'] },
     { name: 'Richard', favoriteIceCreams: ['Cookies & Cream', 'Mint Chocolate Chip', 'Chocolate', 'Vanilla'] },
     { name: 'Amanda', favoriteIceCreams: ['Chocolate', 'Rocky Road', 'Pistachio', 'Banana'] },
     { name: 'Andrew', favoriteIceCreams: ['Vanilla', 'Chocolate', 'Mint Chocolate Chip'] },
     { name: 'David', favoriteIceCreams: ['Vanilla', 'French Vanilla', 'Vanilla Bean', 'Strawberry'] },
     { name: 'Karl', favoriteIceCreams: ['Strawberry', 'Chocolate', 'Mint Chocolate Chip'] }
 ];

let iceCreamTotals = data.map((iceCream) => {
    iceCream.favoriteIceCreams.reduce((iceCreamNames, name) => {
        if (name in allNames){
            iceCreamNames[name]++
        } else {
            iceCreamNames[name] = 1;
        }
        return iceCreamNames
    }, {})
})

Here is a solution without using foreach:

let iceCreamTotals = data
    .reduce( (accumulator, currentValue) => {
        return currentValue.favoriteIceCreams.reduce( (accumulator2, iceCream) => {
            accumulator.push(iceCream)
            return accumulator
        }, [] )
    }, [] )
    .reduce( (accumulator, currentValue) => {
         if ( currentValue in accumulator ) {
            accumulator[currentValue]++;
        } else {
            accumulator[currentValue] = 1;
        }
        return accumulator;
    }, {} )

console.log(iceCreamTotals)