JSFiddle - React, Tailwind, and code Playground

HTML

<div id="1"></div>
<div id="2"></div>
<div id="3"></div>

JavaScript

$.reduce = function(elems, callback, memo, arg) {
    for (var i = 0, length = elems.length; i < length; i++) {
        memo = callback(elems[i], i, memo, arg);
    }

    return memo;
};

$.fn.reduce = function(callback, memo) {
    return jQuery.reduce(this, function(elem, key, memo) {
        return callback.call(elem, elem, key, memo);
    }, memo);
};

var a = $("div").reduce(function(val, key, memo) {
    return (memo += Number(this.id));
}, 0);

var b = $.reduce([1,2,3], function(val, key, memo) {
    return memo += val;
}, 0);

console.log(a);
console.log(b);