addEventListener error in IE8 - addeventlistener

Question

I'm getting an error message in ie8: Object doesn't support property or method 'addEventListener'. How can I fix this? I've seen adding an else statementand changing addEventListener to attachEvent. However, I am a bit green in the land of js and not sure where that should go, I did try a few ways.
$(document).ready(function() {
// Off canvas menu
var $slider = document.querySelector('#slider');
var $toggle = document.querySelector('.toggle-nav');
var $toggle2 = document.querySelector('nav .toggle-nav');
// var $link = document.querySelector('.link > a');
$toggle.addEventListener('click', function() {
var isOpen = $slider.classList.contains('slide-in');
$slider.setAttribute('class', isOpen ? 'slide-out' : 'slide-in');
$('#slider').animate({'right': '100%'}, 400);
});
$toggle2.addEventListener('click', function() {
var isOpen = $slider.classList.contains('slide-in');
$slider.setAttribute('class', isOpen ? 'slide-out' : 'slide-in');
$('#slider').animate({'right': '0'}, 300);
});
var toggleDataAttr = function(parentElem, toggleElem, opt1, opt2, dataAttr) {
var toggleElem = parentElem.querySelector(toggleElem);
toggleElem.setAttribute(dataAttr, toggleElem.getAttribute(dataAttr) === opt1 ? opt2 : opt1);
};
var toggle_li = document.querySelectorAll('li');
for (var i = 0; i < toggle_li.length; i++) {
toggle_li[i].onclick = function() {
toggleDataAttr(this, '.toggleContent', 'closed', 'open', 'data-state');
toggleDataAttr(this, '.toggleIcon', 'down', 'up', 'data-icon');
};
}
});

Answer 1

addEventListener() is not supported in IE8 and lower (more info here: http://www.w3schools.com/jsref/met_document_addeventlistener.asp), instead you need to use attachEvent() in these browsers.
You can use it like this:
if(element.addEventListener()) {
element.addEventListener('click', myFunction(), true);
} else if(element.attachEvent()) {
element.attachEvent('click', myFunction());
}
This way to do it makes it multi-browser compatible.