How to correctly send a patch request in frontend and backend in node environment

Hello, I am trying to update a resource using patch method. I am completely unable to do so. I am using only node and no react.

My Mongo Db Schema

I have to update the desc field. my backend patch request is working. The code for patch request is

At postman it is working fine

you can see the record in the dB is updated

I need to update it through a form having a text area.

I have attached a function in my frontend JavaScript to the submit button for creating a fetch request

Below is my Form in html.

Here is how the button is linked with the function

This is the error I am getting

Here is my frontend console

My Fetch Request for Patch Javascript Codes

await fetch(window.location.href, {
        method: 'PATCH',
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded'
          },
        credentials: 'include',  
        body: JSON.stringify({
          desc: abc,
        })
        
      })
        .then((response) =>  {
            console.log(response);
            return response;
        })
        .then((data) => {
            console.log(data);
        })
  };