CallBack,CallBack Hell

What is CallBack?

• It is a function that is passed as an argument to another function
• callback allows another function to call
• A function can accept another function as argument

function greet(name,callback) {
    console.log("Hello, " + name);
    callback();
    }

    function sayBye() {
    console.log("Goodbye!");
    }

    greet("Ajay", sayBye);

When to use callback?

• when performing asynchronous operations such as network requests
• It is used to handle events such as user input,mouse clicks

What is CallBack Hell?

Multiple nested callback functions make code more difficult to read and maintain so that we call it as callback hell.

 setTimeout(()=>{
           console.log("step1");
           setTimeout(()=>{
            console.log("step2");
            setTimeout(()=>{
                console.log("step3");
                setTimeout(()=>{
                    console.log("step4")
                },1000)
            },1000)
           },1000)
       },1000) 

Problems with callback hell:

• Readability
• Error Handling
• Maintaining

Solutions to avoid callback hell

• Promises
• Async/Await