#!/usr/bin/env js
var pEnlarged 
function dblSize() {
    var pElements = document.getElementsByTagName('p');
    
 if (pElements.length == 0) {
        alert('p要素はこの文書にありません。');
 } else {
     if (!pEnlarged) {
         for (let i of pElements) {
             i.style.fontSize = '200%';
         }
         pEnlarged = true;
     }
     else {
         for (let i of pElements) {
             i.style.fontSize = '100%'; 
         }
         pEnlarged = false;
     }
 }
}
document.addEventListener("DOMContentLoaded", function(e) {
    document.body.addEventListener("click", dblSize);
});