JavaScript is a dynamic object-oriented programming language, which is designed with flexi-ble programming mechanisms. JavaScript is widely used in developing sophisticated software systems, especially web applications. Despite of its popularity, there is a lack of software tools that support JavaScript for software engineering clients. Dataflow analysis approxi-mates software behavior by analyzing the program code; it is the foundation for many soft-ware tools. However, several unique features of JavaScript render existing dataflow analysis techniques ineffective. Reflective constructs, generating code at runtime, make it difficult to acquire the complete program at compile time. Dynamic typing, resulting in changes in object behavior, poses a challenge for building accurate models of objects. Different functionalities can be observed when a function is variadic; the variance of the function behavior may be caused by the arguments whose values can only be known at runtime. Object constructors may be poly-morphic such that objects created by the same constructor may contain different properties. In addition to object-oriented programming, JavaScript supports paradigms of functional