PHP Snippet 1:
<input type="button" value="Edit" onclick="window.location.replace('http://localhost/index.php?username='<?=$_POST['username']?>'&email='<?=$_POST['email']?>');return true;"/>
PHP Snippet 2:
<input type="button" value="Edit" onclick="window.location.href = 'http://localhost/index.php?username=<?=$_POST['username']?>&email=<?=$_POST['email']?>';return true;"/>
PHP Snippet 3:
<input type="button" value="Edit" onclick="window.location.replace('http://localhost/index.php?username='<?=$_POST['username']?>'&email='<?=$_POST['email']?>');return true;"/>
PHP Snippet 4:
<input type="button" value="Edit" onclick="window.location.replace('http://localhost/index.php?username=<?=$_POST['username']?>&email=<?=$_POST['email']?>');return true;"/>