JSFiddle - React, Tailwind, and code Playground

JavaScript

var basketItems = ['1','3','1','4','4'];
var returnObj = {};

$.each(basketItems, function(key,value) {

var numOccr = $.grep(basketItems, function (elem) {
    return elem === value;
}).length;
    returnObj[value] = numOccr
});
console.log(returnObj);