How do I prevent my page to reload or refresh on submitting the html form (textarea) on a button click? Please help me out. Thank you. : Here is the form------>

<form method="post">
       <label class="left margin-left-10">Involve in discussion</label>
       <br>
      <textarea name="chat" placeholder="Write.." cols="20" wrap="soft" maxlength="1000" class="left"></textarea>
      <button name="sendmsg" class="background-none text-white background-primary-hightlight text-s-size-12">Send</button>
<form>