JS callback examples

script.js

// Custom javascript
function fullName(firstName, lastName, callback) {
  console.log('My name is ' + firstName + ' ' + lastName);
  callback(lastName);
}

var greeting = function(ln) {
  console.log("Welcome Mr. " + ln);
}

///

window.watchResize = function(callback) {
  var resizing;

  function done() {
    clearTimeout( resizing );
    resizing = null;
    // Run callback after finish window resize
    callback();
  }

  window.onresize = function() {
    if ( resizing ) {
      clearTimeout( resizing );
      resizing = null;
    }
    resizing = setTimeout( done, 200 );
  }

  // Run callback on pageload
  callback();
}

var browserWidth = 0;

window.watchResize(function() {
  browserWidth = window.innerWidth || document.body.offsetWidth;
  console.log('Browser width ' + browserWidth)
});

// Create and append image element
var firstParagraph = document.getElementsByTagName('p')[0];
var img = document.createElement('img');
img.setAttribute('alt', 'Bilde');
img.setAttribute('src', 'http://gfx.nrk.no/front/2015/02/27/c=395,287,1261,580;w=198;h=91;43500.jpg');
firstParagraph.appendChild(img);