Why don’t the modern browsers support PUT and DELETE form methods?

Some web frameworks (e.g. Ruby on Rails) get around that by including a hidden _method parameter in the form with the value of the “actual” method, e.g.:

<form action="/posts/xxxxx" method="POST">
    <input type="hidden" name="_method" value="DELETE">
    <input type="submit" value="delete">
</form>

The framework then rewrites the request on the server side before processing to use the value of the _method parameter as the HTTP method.

Don’t know if this helps you.