[рони]

moslem,
для медитации

var res = {
    "p1": firstPi,
    "p2": secondPi,
    "pid": defPi
};
Object.keys(res).forEach(function(key) {
    var arr = res[key];
    [].forEach.call(document.querySelectorAll("." + key), function(el, i) {
        el.value == arr[i] ? el.classList.remove("error") : el.classList.add("error")
    })
});