How the JavaScript engine works

JavaScript runs on a variety of devices- a phone, laptop, tv and even IoT devices. The resources available to a JavaScript engine can vary a lot. A JavaScript engines performs the following tasks: 1- Compiler optimization 2- Garbage collection 3- Hot code management 4- Caching 5- Other runtime aspects of the program Whenever any device loads JS, it loads, parses and then executes the js code inside the script.