The social networking giant created the isInputPending API to address a problem it identified in measuring user interactions with its service: the fact that queueing time was consistently producing some of the biggest delays.
The isInputPending API introduces the concept of interrupts for user inputs. As Facebook's Nate Schloss and Andrew Comminos explained in a blog post, instead of making a choice between loading pages fast and responding to events fast, the new API "hooks into Chrome's compositor-side input queue to intercept events before they're posted to the main thread. As all processing of these input events is done off the main thread, calls to isInputPending do not use many computational resources and should be very quick. This allows developers to invoke the API frequently and maximize responsiveness."
As the isInputPending API is part of an origin trial, its future in Chrome is not guaranteed. If feedback is positive, it could become a permanent feature that ultimately helps developers "get rid of these noticeable queueing delays and make the web experience faster and more fluid" for users.
Facebook says it hopes to make further contributions to open-source browsers, and hinted that it could contribute additional APIs down the line in what represents a new approach for the company to influence web standards.