Caching Responses

bestfetch includes a sophisticated system for caching responses.

Configuring the Caching Behavior

Use the cachePolicy option when calling bestfetch() to control when the cache is used. Supported values are:

• "cache-first": The cache is checked to see if a response already exists for the request. If a response is found, then it will be returned, and no network request will be made. If no response exists in the cache, then a network request will be made.
• "network-only": The cache is ignored, and a network request is always made.
• "cache-only": If a response exists in the cache, then it will be returned. If no response exists in the cache, then the Promise will reject to a CacheMissError.

The following example shows how to specify the "network-only" option:

bestfetch('/api/books/2', { cachePolicy: 'network-only' })
  .then(res => {
    console.log('Got the book', res.data);
  });

The Default Behavior

The default value of cache-policy is determined by the methed of the request:

The default value for less commonly used methods is:

When to Change This Behavior

The default behavior is designed to work for traditional "RESTful" APIs. There are a couple of common situations where this default will not work, and where you will need to specify cachePolicy yourself:

• GraphQL: many GraphQL implementations use POST for all requests (queries and for mutations).
• REST APIs: Sometimes, APIs will use POST for retrieving data instead of GET.

Cache Invalidation

Responses that are added to the cache are never invalidated unless you configure how you would like for them to be invalidated. For more, refer to the guide on invalidating cached responses.

Directly Accessing the Cache

There may come a time when you need to directly read or write to the response cache. You can use the responseCache export from this library to do this. Learn more in the API documentation for responseCache.

Learn More

To learn more about how this algorithm works, and also how you can change its behavior, check out the Identical Requests guide.