function dblSize() {
    var pElements = document.querySelectorAll("p");
    if (pElements.length == "0") {
	alert('p?????????????');	
    } else {
	for (let niya of pElements) {
            niya.style.fontSize = '200%';
        }
    }
}
window.addEventListener("load", function(e) {
    document.body.addEventListener("click", dblSize);
});