$ show apache/echarts
Apache ECharts is a mature, open-source JavaScript visualization library for building interactive charts and dashboards in web browsers. It provides a comprehensive set of chart types (line, bar, pie, scatter, map, radar, treemap, sunburst, sankey, etc.), coordinate systems (cartesian, polar, geo, parallel, calendar, matrix), and interactive components (tooltip, legend, dataZoom, visualMap, brush, timeline). The library follows a modular architecture where each chart, component, and renderer is registered via an `install` function, enabling tree-shaking and custom builds. The core rendering engine is ZRender, supporting both Canvas and SVG output, with server-side rendering (SSR) support for SVG. ECharts uses a declarative option-based API (`setOption`) and provides extensive TypeScript type definitions, internationalization (30+ locales), and theming. The codebase is well-structured with clear separation of concerns: models handle option parsing and state, views handle rendering, and a scheduler manages the rendering pipeline (layout, visual, animation). The library is production-grade, with a large test suite including unit tests, visual regression tests, and performance benchmarks. It is actively maintained by the Apache Software Foundation with frequent releases and a large community.
The LLM identified 6 files worth highlighting for reuse:
A generic KD-tree implementation for nearest-neighbor and k-nearest-neighbor search in multi-dimensional space. Used internally for parallel coordinates and other spatial queries. The implementation is self-contained, with a clean API (build, nearest, add, remove) and no dependencies on ECharts internals, making it directly reusable in any JavaScript project requiring spatial indexing.
An efficient data differencing utility that compares two arrays of data items and produces add/update/remove operations. Supports one-to-one and multiple-key diff modes, and is used extensively across chart views for incremental rendering updates. The implementation is generic, with no coupling to ECharts data structures, and can be extracted for any application needing efficient list diffing.
An implementation of the quickselect algorithm for finding the k-th smallest element in an array in O(n) average time. Used in axis nice tick computation to find median or percentile values. The function is standalone, well-optimized with in-place partitioning, and can be reused in any project requiring order statistics.
A throttle utility that provides `createOrUpdate` and `clear` methods for managing rate-limited function calls. Supports both leading and trailing edge execution, and is used to limit the frequency of expensive operations like data zoom updates and tooltip refreshes. The implementation is self-contained and follows a reusable pattern for any JavaScript application needing throttling.
A factory function `createSymbol` that generates ZRender path elements for built-in symbol types (circle, rect, diamond, pin, arrow, triangle, etc.) with customizable size, rotation, and color. It also handles symbol registration and provides a consistent interface for creating visual markers. While it depends on ZRender for path creation, the pattern of a symbol factory with registration is reusable in any graphics library.
A set of utilities for class management: `enableClassExtend` for creating extendable classes with static `extend` method, `enableClassManagement` for registering subclasses by type, and `enableClassCheck` for runtime type checking. These are used throughout ECharts for models, views, and scales. The pattern is generic and can be extracted for any JavaScript project needing a lightweight class system with registration and inheritance.