How to make a element wait a few seconds before showing, using javascript?
You can make an element wait a few seconds before showing by using the setTimeout function in JavaScript. Here's an example of how you can do this:

```
<div id=myDiv>This is some text that will be hidden.</div>

<script>
  setTimeout(function() {
    document.getElementById(myDiv).style.display = block;
  }, 5000);
</script>
```

In this example, the setTimeout function waits for 5000 milliseconds (5 seconds), and then sets the display property of the element with the id of myDiv to block, which makes it visible. This feature set can be expanded to different elements by replacing which id is retrieved and the time can be adjusted to fit to your needs.
Can you add a code wherein a prompt pops out after the set timeout?
Sure, here's an example of how you can display a prompt after the setTimeout function:

<div id=myDiv>This is some text that will be hidden.</div>

<script>
  setTimeout(function() {
    document.getElementById(myDiv).style.display = block;
    var response = prompt(Do you want to continue?);
    if (response === 'yes') {
      // do something if the user says yes
    } else {
      // do something if the user says no or closes the prompt
    }
  }, 5000);
</script>


In this example, after the setTimeout function has waited for 5000 milliseconds (5 seconds), the display property of the element with the id of myDiv is set to block, making it visible. Then, a prompt will appear asking the user if they want to continue. Based on their response, you can do something, such as redirecting them to another page, displaying a message, or any other desired action.