A method includes, by one or more computing devices, determining JavaScript statements to be evaluated, parsing the JavaScript statements, translating the JavaScript statements into Java bytecodes and JavaScript-specific instructions, executing the Java bytecodes in a Java execution engine, calling a JavaScript run-time engine from the Java execution engine, handling one or more semantic operations associated with the JavaScript-specific instructions through use of the JavaScript run-time engine, and providing return values to the Java execution engine. The statements are configured for execution on a computing device. The set of Java bytecodes and JavaScript-specific instructions is configured to conduct symbolic execution of one or more portions of the JavaScript statements. The symbolic execution is configured to evaluate the JavaScript statements.