Method detectContentTypeHeader

packages/common/http/src/request.ts:480–517

* Examine the body and attempt to infer an appropriate MIME type * for it. * * If no such type can be inferred, this method will return `null`.

()

   * If no such type can be inferred, this method will return `null`.
   */
  detectContentTypeHeader(): string | null {
    // An empty body has no content type.
    if (this.body === null) {
      return null;
    }
    // FormData bodies rely on the browser's content type assignment.
    if (isFormData(this.body)) {
      return null;
    }
    // Blobs usually have their own content type. If it doesn't, then
    // no type can be inferred.
    if (isBlob(this.body)) {
      return this.body.type || null;
    }
    // Array buffers have unknown contents and thus no type can be inferred.
    if (isArrayBuffer(this.body)) {
      return null;
    }
    // Technically, strings could be a form of JSON data, but it's safe enough
    // to assume they're plain strings.
    if (typeof this.body === 'string') {
      return TEXT_CONTENT_TYPE;
    }
    // `HttpUrlEncodedParams` has its own content-type.
    if (this.body instanceof HttpParams) {
      return 'application/x-www-form-urlencoded;charset=UTF-8';
    }
    // Arrays, objects, boolean and numbers will be encoded as JSON.
    if (
      typeof this.body === 'object' ||
      typeof this.body === 'number' ||
      typeof this.body === 'boolean'
    ) {
      return JSON_CONTENT_TYPE;
    }
    // No type could be inferred.
    return null;
  }

  clone(): HttpRequest<T>;
  clone(