JSFiddle - React, Tailwind, and code Playground

JavaScript

function filter(a, fun) {
    var ret = { good: [], bad: [] };
    for (var i = 0; i < a.length; i++)
        if (fun(a[i]))
            ret.good.push( a[i] );
        else
            ret.bad.push( a[i] );
    return ret;
}


console.log(filter([0,1,2,3], function(a) { return a % 2 }));