what are callback functions javascript code example

Example 1: what are callback functions

// A function which accepts another function as an argument
// (and will automatically invoke that function when it completes - note that there is no explicit call to callbackFunction)
funct printANumber(int number, funct callbackFunction) {
    printout("The number you provided is: " + number);
}

// a function which we will use in a driver function as a callback function
funct printFinishMessage() {
    printout("I have finished printing numbers.");
}

// Driver method
funct event() {
   printANumber(6, printFinishMessage);
}

Example 2: javascript callback

// Create a callback in the probs, in this case we call it 'callback'
function newCallback(callback) {
  callback('This can be any value you want to return')
}

// Do something with callback (in this case, we console log it)
function actionAferCallback (callbackData) {
  console.log(callbackData)
}

// Function that asks for a callback from the newCallback function, then parses the value to actionAferCallback
function requestCallback() {
  newCallback(actionAferCallback)
}

Example 3: create callback function javascript

function add(a, b, callback) {
  if (callback && typeof(callback) === "function") {
    callback(a + b);
  }
}

add(5, 3, function(answer) {
  console.log(answer);
});