JSFiddle - React, Tailwind, and code Playground

JavaScript

var array_elements = ["2","1","2","2","3","4","3","3","3","5"];

var result = array_elements.reduce(function(p, c){
    if (c in p) {
       p[c]++;
    } else {
        p[c]=1;
    }
    return p;
}, {});

console.log(result);