Headers class Null safety

The interface of the Fetch API allows you to perform various actions on HTTP request and response headers. These actions include retrieving, setting, adding to, and removing headers from the list of the request's headers. A object has an associated header list, which is initially empty and consists of zero or more name and value pairs. You can add to this using methods like append() (see Examples.) In all methods of this interface, header names are matched by case-insensitive byte sequence. For security reasons, some headers can only be controlled by the user agent. These headers include the forbidden header names and forbidden response header names. A Headers object also has an associated guard, which takes a value of immutable, request, request-no-cors, response, or none. This affects whether the set(), delete(), and append() methods will mutate the header. For more information see Guard. You can retrieve a object via the Request.headers and Response.headers properties, and create a new object using the Headers.Headers() constructor. An object implementing can directly be used in a for...of structure, instead of entries(): for (var p of myHeaders) is equivalent to for (var p of myHeaders.entries()).

Note: you can find more out about the available headers by reading our HTTP headers reference.

Available Extensions
  • @experimental
  • @JS()
  • @staticInterop


Headers([dynamic init])


hashCode int
The hash code for this object.
runtimeType Type
A representation of the runtime type of the object.


noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
toString() String
A string representation of this object.


operator ==(Object other) bool
The equality operator.