Request.bodyUsed
  The read-only bodyUsed property of the
  Request interface is a boolean value that indicates
  whether the request body has been read yet.
Value
A boolean value.
Examples
const request = new Request('/myEndpoint', {
  method: 'POST',
  body: 'Hello world'
});
request.bodyUsed; // false
request.text().then(function(bodyAsText) {
  console.log(request.bodyUsed); // true
});
Specifications
| Specification | 
|---|
| Fetch Standard  # ref-for-dom-body-bodyused①  | 
Browser compatibility
BCD tables only load in the browser