CSP: prefetch-src
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The HTTP Content-Security-Policy (CSP)
prefetch-src directive specifies valid resources that may
be prefetched or prerendered.
| CSP version | 3 |
|---|---|
| Directive type | Fetch directive |
default-src fallback |
Yes. If this directive is absent, the user agent will look for the
default-src directive.
|
Syntax
One or more sources can be allowed for the prefetch-src policy:
Content-Security-Policy: prefetch-src <source>;
Content-Security-Policy: prefetch-src <source> <source>;
Sources
<source> can be any one of the values listed in CSP Source Values.
Note that this same set of values can be used in all fetch directives (and a number of other directives).
Example
Prefetch resources do not match header
Given a page with the following Content Security Policy:
Content-Security-Policy: prefetch-src https://example.com/
Fetches for the following code will return network errors, as the URLs provided do not
match prefetch-src's source list:
<link rel="prefetch" href="https://example.org/" />
<link rel="prerender" href="https://example.org/" />
Specifications
| Specification |
|---|
| Content Security Policy Level 3 # directive-prefetch-src |
Browser compatibility
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