JavaScript Runtime Instrumentation via Chrome DevTools Protocol

The post describes an experimental approach to reverse engineering and debugging JavaScript at runtime using Chrome DevTools Protocol (CDP). The method allows hooking functions, inspecting or modifying arguments and local variables, and overriding return values—limited to synchronous functions. It also supports conditional stepping (stepIn, stepOut, stepOver) and works within closures or non-exported code. The implementation relies on CDP’s debugger breakpoints and runtime evaluation.