Dan Abramov - Live React: Hot Reloading with Time Travel at react-europe 2015

Caption notes

Dan Abramov starts with the frustration of refreshing an application, losing state and repeating interactions, then explains his contemporary designs for React Hot Loader and Redux. He separates replaceable method implementations from retained instance state, and reduces state transformation to a function taking previous state and an action and returning new state. Recorded actions can then serve as inputs for recomputing state, under his stated conditions of avoiding pervasive mutation and moving side effects to the edges. This is not automatic rewind for an arbitrary application. The reading uses self-contained spoken explanations without verifying the live code or screen results. The talk also distinguishes existing features from unreleased tools and ideas such as exporting tests; the question-period bridge to external debugging tools remains a proposal, not a description of current product functionality.