<Tr> <Td> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> </Td> </Tr> <Ul> <Li> </Li> <Li> </Li> <Li> </Li> </Ul> <P> A JavaScript engine is a program or interpreter which executes JavaScript code . A JavaScript engine may be a traditional interpreter, or it may utilize just - in - time compilation to bytecode in some manner . Although there are several uses for a JavaScript engine, it is most commonly used in Web browsers . </P> <P> Before the second browser war in 2008 - 2009, JavaScript engines (also termed JavaScript interpreter or JavaScript implementation) were simply interpreters that read and executed JavaScript source code . </P>

Portion of browser software that reads and executes javascript