Turf.js
Browser-side spatial analysis: buffers, measurement and interpolation. Every tutorial and API topic has a full English page on this site, with runnable code taken from the original examples.
13TUTORIALS
45API TOPICS
32RUNNABLE EXAMPLES
Tutorials
All 13 →API reference
All 45 →English edition hosted on jingweizhi.com. Chinese originals: /turf/. Pages adapted from official docs carry attribution at the bottom.