while trying post method throwing invalid csrfToken error - how to resolve this about server HOT 2 CLOSED

See the CSRF token guide:

For POST, PUT and DELETE requests a valid CSRF token with the field name of _csrf must be sent as well. The local variable is set by server.js so you can include it like this:

<form action="/" method="POST">
  <input name="firstname">
  <input type="submit" value="Contact us">
  <input type="hidden" name="_csrf" value="{{csrf}}">
</form>

If you are using an API from Javascript, such as the new fetch() you can handle it this way:

<!-- within your main template -->
<script>
  window.csrf = '{{csrf}}';
</script>

// Within your javascript.js/bundle.js/app.js
fetch('/', {
  method: 'POST',
  body: 'hello world',
  credentials: 'include',  // Important! to maintain the session
  headers: { 'csrf-token': csrf }  // From 'window'
}).then(...);

Or you could also just disable it if you know what you are doing:

server({ security: { csrf: false } }, ...);

from server.

For extra context (heh) for APIs, the CSRF token is in your context as ctx.csrf so you can pass it along e.g. on login:

get('/login', ctx => {
  // Do your logic

  return {
    user,
    csrf: ctx.csrf
  };
});

from server.