callback functions

30daysofJavascript

by Rajdeep Chandra

JavaScript

// simple callback

let x = function() {
  console.log("this is my first function")
}

let y = function(callback) {
  console.log("this is my second function");
  callback();
}
y(x);

//real use of callback function

let add = function(a, b) {
  return a + b;
}

let multiply = function(a, b) {
  return a * b;
}

let doWatever = function(a, b) {
  console.log(`my return number is ${a} , ${b}`)
}

let calc = function(num1, num2, callback) {
  //checking whether the callback is function or not
  if (typeof callback === 'function') {
    return callback(num1, num2);
  } else {
 
  }
}

console.log(calc(2, 3, doWatever));

//OR

console.log(calc(2, 3, function(a, b) {
  return a + b;
}));


//few interesting examples

let myArr = [
{value:1, name:'apple'},
{value:4, name:'cabbage'},
{value:8, name:'banana'}
]

myArr.sort(function(val1,val2){
	if(val1.name < val2.name){return -1}
  else {
  return 1
  }
})


console.log(myArr)