main.js

var customName = document.getElementById('#customname');
var randomize = document.querySelector('.randomize');
var story = document.querySelector('.story');

function randomValueFromArray(array){
  return array[Math.floor(Math.random()*array.length)];
}

var storyText = 'It was 94 farenheit outside, so :insertx: went for a walk. When they got to :inserty:, they stared in horror for a few moments, then :insertz:. Bob saw the whole thing, but was not surprised — :insertx: weighs 300 pounds, and it was a hot day.'
var insertX = ['Willy the Goblin','Big Daddy','Father Christmas'];

var insertY = ['the soup kitchen','Disneyland' ,'the White House'];
               
var insertZ = ['spontaneously combusted' ,'melted into a puddle on the sidewalk' ,'turned into a slug and crawled away'] ;   
                          

               randomize.addEventListener('click', result);

               function result() {
                 var newStory = storyText;
                 var xItem = randomValueFromArray(insertX);
                 var yItem = randomValueFromArray(insertY);
                 var zItem = randomValueFromArray(insertZ);
                 newStory = newStory.replace(':insertx:',xItem);
                 newStory = newStory.replace(':insertx:',xItem);
                 newStory = newStory.replace(':inserty:',yItem);
                 newStory = newStory.replace(':insertz:',zItem);
               
                 if(customName.value !='') {
                   var name = customName.value;
                   newStory = newStory.replace('Bob',name);
                 }
               
                 if(document.getElementById("uk").checked) {
                   var weight = Math.round(300*0.071429)+'stones';
                   newStory = newStory.replace('300 pounds',weight);
                   var temperature =  Math.round(((94-32)*5)/9)+'centigrade';
                   newStory = newStory.replace('94 farenheit',temperature);
                 }
               
                 story.textContent = newStory;
                 story.style.visibility = 'visible';
               }