The drawback of Using the callback function

Callback function

• A callback function is a function passed into another function as an argument, which is then invoked inside the outer function to complete some kind of routine or action.
• Callback functions are used to achieve asynchronous behaviour in JavaScript

  Drawback of using the Callback function

  There are two drawbacks of using the callback function
• The diamond problem or callback hell
• Inversion of Control

  The diamond problem / callback hell

• When we have multiple callbacks nested inside each other then it is called a callback hell
• Because of this debugging and maintaining the code becomes difficult.
• It is called a diamond or pyramid problem because nested callbacks look that way Example :

Inversion of Control / Trust issues with callback

• Sometimes callback functions do not behave the way they should.
• One classic example is :
  assume we have a set timeout function which has a timer of 10 sec
  But in the global space we have written so many lines that the time taken to execute those statements is more than 10 sec then as a result the event loop will never find the call stack empty and hence, even after a long time the set timeout has expired the callback function passed inside it will never get executed the way we wanted it to get executed