Request.cache

The cache read-only property of the Request interface contains the cache mode of the request. It controls how the request will interact with the browser's HTTP cache.

Syntax

var currentCacheMode = request.cache;

Value

A RequestCache value. The available values are:

• default — The browser looks for a matching request in its HTTP cache.
  • If there is a match and it is fresh, it will be returned from the cache.
  • If there is a match but it is stale, the browser will make a conditional request to the remote server. If the server indicates that the resource has not changed, it will be returned from the cache. Otherwise the resource will be downloaded from the server and the cache will be updated.
  • If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.
• no-store — The browser fetches the resource from the remote server without first looking in the cache, and will not update the cache with the downloaded resource.
• reload — The browser fetches the resource from the remote server without first looking in the cache, but then will update the cache with the downloaded resource.
• no-cache — The browser looks for a matching request in its HTTP cache.
  • If there is a match, fresh or stale, the browser will make a conditional request to the remote server. If the server indicates that the resource has not changed, it will be returned from the cache. Otherwise the resource will be downloaded from the server and the cache will be updated.
  • If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.
• force-cache — The browser looks for a matching request in its HTTP cache.
  • If there is a match, fresh or stale, it will be returned from the cache.
  • If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.
• only-if-cached — The browser looks for a matching request in its HTTP cache.
  • If there is a match, fresh or stale, if will be returned from the cache.
  • If there is no match, the browser will return an error.
  The "only-if-cached" mode can only be used if the request's mode is "same-origin". Cached redirects will be followed if the request's redirect property is "follow" and the redirects do not violate the "same-origin" mode.

Example

// Download a resource with cache busting, to bypass the cache
// completely.
fetch("some.json", {cache: "no-store"})
  .then(function(response) { /* consume the response */ });

// Download a resource with cache busting, but update the HTTP
// cache with the downloaded resource.
fetch("some.json", {cache: "reload"})
  .then(function(response) { /* consume the response */ });

// Download a resource with cache busting when dealing with a
// properly configured server that will send the correct ETag
// and Date headers and properly handle If-Modified-Since and
// If-None-Match request headers, therefore we can rely on the
// validation to guarantee a fresh response.
fetch("some.json", {cache: "no-cache"})
  .then(function(response) { /* consume the response */ });

// Download a resource with economics in mind!  Prefer a cached
// albeit stale response to conserve as much bandwidth as possible.
fetch("some.json", {cache: "force-cache"})
  .then(function(response) { /* consume the response */ });

Specifications

Browser compatibility

See also

• ServiceWorker API
• HTTP access control (CORS)
• HTTP