Any way to differentiate array key types in js? arr[1] !== than arr["1"]

Question

I was trying to solve a most popular item in array problem.

I found some O(n) solutions using maps but nothing that quite works when you have mixed data types, let's say

[1,2,1,3,"1","a"]

The "1" get's mixed with the 1. Any chance I can override comparison within JS? Or any O(n) solution that might fix it?

That was the most popular array element that I was using, taking in consideration that you can have more than one with the same amount:

function getMostFrequent(array) {

    if (array.length == 0)
        return null;

    let mapEl = {};
    let maxEl = [];
    let maxCount = 1;

    for (let i = 0; i < array.length; i++) {
        let el = array[i];

        if (mapEl[el] == null) {
            mapEl[el] = 1;
        } else {
            mapEl[el]++;
        }

        if (mapEl[el] > maxCount) {
            maxCount = mapEl[el];
            maxEl = [el];
        } else if (mapEl[el] === maxCount) {
            maxEl.push(el);
        }

    }

    console.log(maxEl);
    return maxEl;
}

Answer 1

some O(n) solutions using maps

Maps work just fine, because map "keys" can be any type, including numbers, strings, and objects (which are differentiated):

const input = [1,2,1,3,"1", "1", "1", "a"];
const map = new Map();
input.forEach(key => map.set(key, (map.get(key) || 0) + 1));
console.log(
  [...map.entries()].reduce((a, b) => b[1] > a[1] ? b : a)
);

Could also use reduce, which is a bit more appropriate for this situation:

const input = [1,2,1,3,"1", "1", "1", "a"];
const map = input.reduce(
  (map, key) => map.set(key, (map.get(key) || 0) + 1),
  new Map()
);
console.log(
  [...map.entries()].reduce((a, b) => b[1] > a[1] ? b : a)
);

Yes, these are O(N).