const baseElem = document.querySelector("#base");
const heightElem = document.querySelector("#height");
const calcButton = document.querySelector("#calcButton");
const areaElem = document.querySelector("#area");

if(calcButton) {
    calcButton.addEventListener('click', () => {
        let base = Number(baseElem.value);
        let height = Number(heightElem.value);
        let area = calcTriangleArea(base, height);
        areaElem.value = area;
    });
}

const calcTriangleArea = (base, height) => {
    return base * height / 2;
}