The talk was about strong dynamic type checking for JavaScript. The speaker explained that JavaScript is not a strongly typed language, but that TypeScript was invented to address this issue by providing optional static type checking. However, the speaker argued that TypeScript's main selling point is actually the improved developer experience rather than type checking. They introduced their open source library called "Object Model" that provides strong dynamic type checking for JavaScript. The library allows for the creation of dynamic models that bind types to data and perform runtime validation to catch type errors. The speaker discussed the benefits and limitations of the library and recommended using both static and dynamic type checking in JavaScript projects. They also answered questions about the library's stability, performance implications, and alternative approaches to type checking in JavaScript.