Architecture Overview
This library provides a declarative, HTML-based language and runtime for building dynamic and reactive web UIs. It's designed to simplify UI development by extending HTML with features for components, conditionals, and loops, all powered by a robust reactivity system. Developers primarily interact with Marko through its template syntax, writing .marko files that are then compiled into efficient JavaScript. The compilation process is key, transforming your UI descriptions into executable logic.
Under the hood, Marko's architecture is driven by a sophisticated compiler and runtime. The Marko Compiler is responsible for transforming your Marko templates into optimized JavaScript code. This process begins with the Marko Parser, which converts Marko template strings into an Abstract Syntax Tree (AST). This AST is then processed by the compiler to generate JavaScript that the Marko Runtime can execute in the browser. The runtime is the engine that brings your components to life, managing their lifecycle, state updates, and DOM manipulation.
The Marko Runtime orchestrates the rendering and updating of components. When a component needs to be displayed or updated, the Marko Renderer is invoked. This renderer, working closely with the Marko Component Lifecycle module, manages the process of mounting, updating, and unmounting components in the DOM. Crucially, the Marko Virtual DOM Diff module plays a vital role in ensuring efficient updates. It compares the previous and new virtual DOM representations of a component to determine the minimal set of changes required to update the actual DOM, minimizing direct manipulations and enhancing performance.
Central to Marko's dynamic nature is its reactivity system, powered by Marko Observable State and Marko Reactivity Effects. The observable state mechanism allows developers to define state that automatically triggers UI updates when it changes. The reactivity effects system then manages these updates, ensuring that only the parts of the UI dependent on the changed state are re-rendered. This forms the backbone of Marko's declarative programming model, where the UI automatically reflects the current state of the application.
What makes Marko special is its seamless blend of familiar HTML syntax with powerful component-based architecture and efficient reactivity. The architectural trade-off here is the initial compilation step, which allows for highly optimized client-side code. For contributors, understanding the flow from the Marko Parser through the Marko Compiler to the Marko Runtime is essential. Beginning in the packages/compiler and packages/runtime-html directories will provide a solid foundation for understanding how templates are transformed and then executed. Familiarity with the Marko Observable State and Marko Reactivity Effects is also crucial for grasping how dynamic updates are handled.