callbackfn in javascript code example

Example 1: callback function js

function greeting(name) {
  alert('Hello ' + name);
}

function processUserInput(callback) {
  var name = prompt('Please enter your name.');
  callback(name);
}

processUserInput(greeting);

Example 2: callback function js

function myDisplayer(some) {  document.getElementById("demo").innerHTML 
  = some;}function myCalculator(num1, num2, myCallback) {  
  let sum = num1 + num2;  
  myCallback(sum);}myCalculator(5, 5, myDisplayer);