Upgrading junky IE8 code with current goodies

23 May 2016 · by David DeSandro

Man, it feels good to cut out all the old junky code and live in the modern day. With new versions of Isotope, Packery, Masonry, and imagesLoaded, I've been upgrading browser support, dropping IE8 & 9, and Android <4. I've been able to remove hundreds of lines of code.

If you're looking to bump up your browser support, here's a run-down of all the code you can upgrade.

Use standard browser properties

Use addEventListener for event binding, rather than a helper like eventie.

// IE8
eventie.bind( element, 'click', function() {...});
// modern browsers
element.addEventListener( 'click', function() {...});

Use classList for changing classes, rather than a helper like classie.

// IE8
classie.add( element, 'is-selected' );
// modern browsers
element.classList.add('is-selected');

Use event.preventDefault().

// IE8
function onClick( event ) {
  if ( event.preventDefault ) {
    event.preventDefault();
  } else {
    event.returnValue = false;
  }
}
// modern browsers
function onClick( event ) {
  event.preventDefault()
}

Use window.pageYOffset for scroll position.

// IE8
var isPageOffset = window.pageYOffset !== undefined;
var scrollX = isPageOffset ? window.pageXOffset : document.body.scrollLeft;
var scrollY = isPageOffset ? window.pageYOffset : document.body.scrollTop;
// modern browsers
window.pageXOffset;
window.pageYOffset;

Use standard textContent for setting text.

// IE8
var docElem = document.documentElement;
var textSetter = docElem.textContent !== undefined ? 'textContent' : 'innerText';

function setText( elem, value ) {
  elem[ textSetter ] = value;
}

setText( element, 'hello world' );
// modern browsers
element.textContent = 'hello world';

CSS support

All browsers now support transition and transform. So I no longer need get-style-property to check vendor properties.

// IE8
// get vendor property for transform
var transformProp = getStyleProperty('transform');
// set position
if ( transformProp ) {
  // supports transform, set transform
  element.style[ transformProp ] = 'translate(40px, 30px)';
} else {
  // does not support transform, set left, top
  element.style.left = '40px';
  element.style.top = '30px';
}

Modern browsers support transform or -webkit-transform, so you don't have to check every vendor prefix.

// modern browsers
// get vendor property for transform
var docElemStyle = document.documentElement.style;
// either transform or WebkitTransform
var transformProp = typeof docElemStyle.transform == 'string' ?
  'transform' : 'WebkitTransform';
// supports transform, set transform
element.style[ transformProp ] = 'translate(40px, 30px)';

New ES5 features

Dropping IE8 and Android 2.3 means you can natively use ES5 features. There are a bunch of new ES5 features, but here are the ones I have actually used.

Array.isArray to check if an object is an array.

// ES4
var objToString = Object.prototype.toString;
function isArray( obj ) {
  return objToString.call( obj ) == '[object Array]';
};

isArray( items );
// ES5
Array.isArray( items );

Array.prototype.indexOf to get the index of a value.

// ES4
function indexOf( ary, value ) {
  for ( var i=0; i < ary.length; i++ ) {
    if ( ary[i] === value ) {
      return i;
    }
  }
  return -1;
}

indexOf( items, value );
// ES5
items.indexOf( value );

Array.prototype.forEach to iterate over an array.

// ES4
for ( var i=0; i < items.length; i++ ) {
  var item = items[i];
  console.log( item );
}
// ES5
items.forEach( function( item ) {
  console.log( item );
});

Array.prototype.filter to create a new array by filtering values.

var numbers = [ 1, 2, 3, 4, 5, 6 ];

// ES4
var evens = [];
for ( var i=0; i < numbers.length; i++ ) {
  var number = numbers[i];
  if ( number % 2 === 0 ) {
    evens.push( number )
  }
}
// ES5
var evens = numbers.filter( function( number ){
  return number % 2 === 0;
});

Array.prototype.map to create a new array by changing values.

// ES4
var doubles = [];
for ( var i=0; i < numbers.length; i++ ) {
  var number = numbers[i];
  doubles.push( number * 2 );
}
// ES5
var doubles = numbers.map( function( number ) {
  return number * 2;
});

Object.create for prototypal inheritance.

function Animal() {
  console.log('I am an animal!')
}

// ES4
Dog.prototype = new Animal();
// constructor function is triggered
// logs 'I am an animal!'
// also, weird syntax
// ES5
Dog.prototype = Object.create( Animal.prototype )
// constructor function not triggered, no console log

And there's more to play with. I've experimented with custom Object getters and setters. These are powerful concepts, but may take some getting used to.


You may have looked twice. ES Five? Isn't ES6 the new hotness?

Metafizzy's libraries are designed to have a wide, diverse user-base. While forward-leaning developers may be itching to use ES6, they still have to step through scaffolding if they want to use it widespread in production. All the above code can be used right now in every browser worth using. No build processes. No transpilers. Straight up vanilla.

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