HTML

disable html form input autocomplete autofill

<form autocomplete="off">
  <input type="text" name="username" autocomplete="off" />
  <!--OR-->
  <input type="text" name="email" autocomplete="off" />
  
  <input type="password" name="password" autocomplete="new-password" />
</form>

disable browser autocomplete

<form method="post" action="/form" autocomplete="off">
[…]
</form>

disable form input autocomplete

<form autocomplete="off" method="post" action="">
    <input autocomplete="false" name="hidden" type="text" style="display:none;">
    ...

disable autocomplete javascript

someForm.setAttribute( "autocomplete", "off" ); 
someFormElm.setAttribute( "autocomplete", "off" );

input disable autocomplete

autocomplete="off"

how to disable autocomplete

<input name="something" autocomplete="new-something" />