April 21, 2017 Javier Eguiluz

A few weeks ago, we added support for asset preloading with HTTP/2 Push. The feedback was so enthusiastic that we decided to improve and expand this feature. In fact, we decided to create a whole new component for it: WebLink.

This new component manages links between resources, not only assets; advising browsers to preload and prefetch resources through HTTP and HTTP/2 pushes. The component implements these specifications: HTML5 Links, Preload, and Resource Hints

All these new features can be used via several Twig functions:

link() , adds the Link HTTP header;

, adds the HTTP header; preload() , preload resources (not only assets);

, preload resources (not only assets); dns_prefetch() , resolves a resource origin as early as possible;

, resolves a resource origin as early as possible; preconnect() , initiates a early connection to a resource (including DNS resolution, TCP handshake, and TLS negotiation);

, initiates a early connection to a resource (including DNS resolution, TCP handshake, and TLS negotiation); prefetch() , indicates to the client that it should prefetch the given resource;

, indicates to the client that it should prefetch the given resource; prerender() , indicates to the client that it should prerender the given resource.

Unlike the previous preloading feature, this component is not only useful for web assets. Being a standalone component means that it can also be used for example to replace resource embedding by HTTP/2 pushes in your APIs.