not a change to an existing thing but i have a feature idea: variables that aren't initialized until the first time they're accessed

  textarea.onkeydown = event => {
  
    // doesn't get the properties until they're accessed
    const get {selectionStart, selectionEnd, value} = textarea;
  
    // doesn't actually call .slice yet
    const get selectedText = value.slice(selectionStart, selectionEnd);
  
    // ...
  
    if (event.key === "Enter") {
  
      // initializes selectedText
      console.log("selected text: " + selectedText);
  
      // uses the same value, doesn't reinitialize it
      selectedText;
    }
  };