Callback function Examples

1. Greet

function welcome(name,cb){

    console.log("Hello: " +name);
    cb(name);

}
function sayBye(name){
    console.log("Bye:" +name);
}
welcome("Jo",sayBye);

Hello: Jo
Bye:Jo

2. Create Account to login

function createAccount(username,password,cb){
console.log("Provide details to login");
cb(username, password);

}
function login(username,password){

    console.log("User logged in:"+username, +password);
}
createAccount("Anees","123", login)

Provide details to login
User logged in:Anees 123

3. Clear interview to get job:

function clearInterview(cb){
    console.log("Selected");
     cb();

}
function gotJob(cb){
    console.log("Got placed");


}
clearInterview(gotJob);

Selected
Got placed

4. Even Number Check:

function check(a,cb){
console.log("Enter the number to check: " +a);
cb(a);
}
function evenNumberorNot(no){

console.log(no%2==0 ? "Even": "odd")

}
check(4,evenNumberorNot);

Enter the number to check: 4
Even

5. setTimeout Example

function fetchData(cb){
console.log("Fetching data");
//setTimeout(function,timeinMilliseconds);
setTimeout(()=>{
            let data={name:"User", age: "30"};
            cb(data);
            },2000);
}
function displayData(data){
    console.log("User:"+data.name, data.age);
}

fetchData(displayData);

Fetching data
User:User 30