> For the complete documentation index, see [llms.txt](https://javascript-1.gitbook.io/javascript/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://javascript-1.gitbook.io/javascript/javascript-runtime.md).

# JavaScript RunTime

### Web API:  **Asynchronous functionality.**

![Asynchronous functionality.](/files/-Lgq7M4iMqbnueqI7hU6)

### Working process:

* When the code executed, JavaScript run time is created.
* When the function are pushed into the call stack, the functions belonged to Web API will be send to the Web API by call stack for he process.
* When the web API receives the function, it will process the functions, and then it is send to the call back queue.
* Then the processed function in the call back queue will be send to the event loop to send to the call stack.
* After receiving the processed function, event loop pushes the function to the call stack, when it is empty. ( waits until the call stack is empty )
* Then the function will be executed in the call stack.


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