JAVASCRIPT

Hello, I am working with front-end development and would like to use pure javascript instead of using jQuery $.IsNumeric(), so what is possible equivalent function of IsNumeric in Javascript? To validate if string/decimal value is number or not.

Hello, I am working with Typescript in Visual Studio IDE, but I am not sure which Typescript version I am using, so how can I check Typescript version in Visual Studio IDE?

Figure i am talking about-:

https://imgur.com/a/T4viIKF

Confusions, "ie" means my interpretation that i am not sure if is correct or not)-:

1) user clicks invoking an event handler.

  i.e when an user event occurs, it makes a javascript call. most likely user event=function call

2) handler's code creates xmlhttprequest object

  i.e that javascript call creates xmlhttprequest in ajax engine.

3) xhr requests file from server

4) server sends the file.

5) NOW I AM CONFUSED.

the terminologies are confusing me. 

like-:

1. a) xhr fires an event. what does that mean? and why to fire an event? Doesn’t user only fire event? Like clicking,pressing some key etc.
2. b) you can attach handler function to event. (maybe it is trying to talk about event handler i.e if event->handlerfunction() )..I am not sure. 

handler fxn then processes the data and displays it.