Find the most frequent occurrences in a list with JavaScript

find-occurrances.js

// List of items to find occurrences in.
const list = ['Tom', 'Fluffy', 'Tom', 'Bella', 'Chloe', 'Tom', 'Chloe'];

// Creates a Map (hash) of occurrence numbers.
const counts = list.reduce((accumulator, val) => {
    // Initialize entry if needed.
    if (!accumulator.has(val)) accumulator.set(val, 0);
    
    // Increment value.
    accumulator.set(val, accumulator.get(val) + 1);
    
    return accumulator;
}, new Map());
// -> Map(4) {"Tom" => 3, "Fluffy" => 1, "Bella" => 1, "Chloe" => 2}

// Convert the counts Map to an Array of Arrays, so we can sort.
const countsArr = [...counts];
// -> [["Tom", 3], ["Fluffy", 1], ["Bella", 1], ["Chloe", 2]]

// Sort descending and grab the first value.
countsArr.sort((a, b) => b[1] - a[1])[0];
// -> ["Tom", 3]


// ===========================
// Pretty unreadable "one liner" version

[...list.reduce((accumulator, val) => {
    if (!accumulator.has(val)) accumulator.set(val, 0);
    return accumulator.set(val, accumulator.get(val) + 1);
}, new Map())].sort((a, b) => b[1] - a[1])[0];