old_contents: var text = ""
  var fieldX = ""
  var fieldY = ""
  var css = ""
  var table = document.getElementsByTagName("tbody").item(0)
  
  function setTableElement(i, j, text, css) {
      table.children[i].children[j].innerHTML = text
      table.children[i].children[j].style = css
  }
  
  function handleTextInput() {
      text = document.getElementById("text").value
  }
  
  function handleFieldXInput() {
      fieldX = document.getElementById("field_x").value
  }
  
  function handleFieldYInput() {
      fieldY = document.getElementById("field_y").value
  }
  
  function handleCssInput() {
      css = document.getElementById("css").value
  }
  
  function handleMyButton() {
  
  }
  
  document.getElementById("text").addEventListener("change", handleTextInput)
  document.getElementById("field_x").addEventListener("change", handleFieldXInput)
  document.getElementById("field_y").addEventListener("change", handleFieldYInput)
  document.getElementById("css").addEventListener("change", handleCssInput)
  document.getElementById("mybutton").addEventListener("click", handleMyButton)
  
new_contents: var text = "";
  var fieldX = "";
  var fieldY = "";
  var css = "";
  var table = document.getElementsByTagName("tbody")[0];
  
  function setTableElement(i, j, text, css) {
      table.children[i].children[j].innerHTML = text;
      table.children[i].children[j].style = css;
  }
  
  function getTableElement(i, j) {
      return table.children[i].children[j];
  }
  
  function handleTextInput() {
      text = document.getElementById("text").value;
  }
  
  function handleFieldXInput() {
      fieldX = document.getElementById("field_x").value;
  }
  
  function handleFieldYInput() {
      fieldY = document.getElementById("field_y").value;
  }
  
  function handleCssInput() {
      css = document.getElementById("css").value;
  }
  
  function handleMyButton() {
  
  }
  
  document.getElementById("text").addEventListener("change", handleTextInput);
  document.getElementById("field_x").addEventListener("change", handleFieldXInput);
  document.getElementById("field_y").addEventListener("change", handleFieldYInput);
  document.getElementById("css").addEventListener("change", handleCssInput);
  document.getElementById("mybutton").addEventListener("click", handleMyButton);
  
subject: Add semicolons