What if submit resubmits data when the submit button is clicked?

Question

PHP

There is a form that substitutes the data from the input field in the URL and opens the link in a new tab:

<form action="https://mysite.ru/search#" method="post" class="search" id="formurl" target="_blank">
  <input type="search" id='search01' name="search2" />
  <button type="submit" name="submit" onclick="formurl.action += encodeURIComponent(search01.value)"  />
</form>

It works, but there is a problem. If you click the submit button again, the new value of the input field will be added to the old one. That is, the link will be like this: https://mysite.ru/search#OLD_VALUENEW_VALUE
Is there any way to fix this? Tried to use reloading the page after submitting, clearing the $_POST data and rummaged through a lot of forums - nothing helped.
Thanks in advance.
The question is closed. The problem was solved in the following way:

<script>
  function update_href(id,value){
    document.getElementById(id).href='https://mysite.ru/search#'+value;
  }
</script>
<input type="text" onchange="update_href('link', this.value );" size=30>
<a href="https://mysite.ru/search#" target="_blank" id="link">Перейти</a>

But anyway, thank you all!

Answer 1

just block the button after pressing it so that you cannot press it twice

Answer 2

Well, either block, as mentioned above, or

... onclick="formurl.action = formAction + encodeURIComponent(search01.value)" ...

Answer 3

Add header("location: landing_page.php"); to the end of the method .
exit;