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Fwd: Intent to Implement: Intersection Observer

From: Ilya Grigorik <igrigorik@google.com>
Date: Thu, 8 Oct 2015 14:16:09 -0700
Message-ID: <CADXXVKoCeyVLCgoc+eeYco9h_u8grk186QUvR79b5T0bxChZcA@mail.gmail.com>
To: public-web-perf <public-web-perf@w3.org>
Cc: Michael Blain <mpb@google.com>, Ojan Vafai <ojan@google.com>
Hey all, fyi... Still in early stages, but this is *highly* relevant to the
many use cases we've discussed on this list around deferred loading,
element visibility, etc. For a more hands-on overview, check out the

Feedback & issues:


---------- Forwarded message ----------
From: Michael Blain <mpb@chromium.org>
Date: Tue, Oct 6, 2015 at 9:10 PM
Subject: Intent to Implement: Intersection Observer
To: blink-dev@chromium.org

*Contact emails*
mpb@chromium.org, ojan@chromium.org


This specification describes an API that can be used to understand the
visibility and position of DOM elements relative to a viewport. The
position is delivered asynchronously and is useful for understanding the
visibility of elements and implementing pre-loading and deferred loading of
DOM content.

Accurately measuring viewability is important for several use cases;
deferred-loading or lazy-loading of content, infinite-scroll lists and
advertising. Because there is no standard way to get viewable information
across browsers, developers have built and rely on a series of
browser-specific hacks and workarounds. Sites rely on scroll handlers and
plugins in situations where they really aren't necessary, impacting
performance. Intersection Observer addresses this need by introducing a new
API to asynchronously report on the relative positions of elements without
interrupting the critical paths of rendering or processing.

*Compatibility Risk*
Low. The rough API and use cases were received positively when meeting with
other browser vendors in Paris in August. Some of the decisions around
behaviors of edge cases need a fresh review though. Notes from Paris:

*Ongoing technical constraints*

*Will this feature be supported on all six Blink platforms (Windows, Mac,
Linux, Chrome OS, Android, and Android WebView)? Yes or no. *

*OWP launch tracking bug*

*Link to entry on the Chrome Platform Status*

*Requesting approval to ship?*
Received on Thursday, 8 October 2015 21:17:16 UTC

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