coverage-istanbul-loader

A Webpack loader that uses Istanbul to add code coverage instrumentation to JavaScript/TypeScript files. Current stable version is 3.0.5. Release cadence is low; last major update was in 2020. Key differentiators include support for modern Istanbul API (istanbul-lib-instrument) and better source map handling compared to the older istanbul-instrumenter-loader. Ships TypeScript definitions. Requires Node >=10 and Webpack 4+. Works with Karma, TypeScript, and custom options.