In this paper, we propose CASCADE, a novel hybrid approach to address the problem of JavaScript code obfuscation. CASCADE works by integrating advanced coding features from Gemini with deterministic transformations using JavaScript IR (JSIR). Using Gemini, we identify important prelude functions that form the basis of obfuscation techniques, and perform code transformations using JSIR to recover semantic elements such as original strings and API names, revealing the original program behavior. It overcomes the limitations of existing static and dynamic deobfuscation techniques, achieving reliability and flexibility while eliminating hundreds or thousands of hardcoded rules. It has already been deployed in Google’s production environment and has been shown to significantly improve JavaScript deobfuscation efficiency and reduce reverse engineering efforts.