Async JS Codevolution

 

     

      




Why async


How ?


Tradional Methdo of Js

setTimeout


To Clear a timeout use

It will ensure that greet function will not run after 2 sec duration




Remember to clear the interval esle it will run forever


  2 cont... funtion will run  only after call stack is free


 



CALLBACKS


Rewriting the code as per their names



Types of Call Back
Sycnhronus Callback
(Same as bove)

Nothing to fancy about synchronus callback

Async Callback



Here, the magic is there so learn it ,revise it


In eg 1 setTime out is hOF and greet() is callback funtion
eg 2: addEventListener is HOF and the fn attaxched to event handler is the callback
as it will only be excute after it isbeen  clicked














This becomes extremely unreadble so promises has been introduced

Promise

'







WEcan pass value to resolve and rejected if we want to add extra bit of info


The value is automactially fetched and it can be accessed


More details

Bothe means same

Howevver,



3. Chaining Promises (solution to callback hell)


3.Promise - static methhods



























n

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