lib/fetch.browser.js
function isValidBody(body) {
  return (
    body === undefined ||
    typeof body === 'string' ||
    (typeof FormData !== 'undefined' && body instanceof FormData) ||
    (typeof URLSearchParams !== 'undefined' && body instanceof URLSearchParams)
  );
}
function isValidBody(body) {
  return (
    body === undefined ||
    typeof body === 'string' ||
    (typeof FormData !== 'undefined' && body instanceof FormData) ||
    (typeof URLSearchParams !== 'undefined' && body instanceof URLSearchParams)
  );
}
function isValidBody ( body ) { return ( body === undefined || typeof body === 'string' || ( typeof FormData !== 'undefined' && body instanceof FormData ) || ( typeof URLSearchParams !== 'undefined' && body instanceof URLSearchParams ) ) ; }
Blob or BufferSource or FormData or URLSearchParams or USVString
Blob or BufferSource or FormData or URLSearchParams or USVString