callback function js code example

Example 1: javascript callback

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

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

processUserInput(greeting);
// The above example is a synchronous callback, as it is executed immediately.

Example 2: callback function js

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

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

processUserInput(greeting);

Example 3: 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 4: 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);
});

Example 5: javascript callback function

const message = function() {  
    console.log("This message is shown after 3 seconds");
}
 
setTimeout(message, 3000);

Example 6: 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);