jQuery window.width doesn't work in Firefox

Question

Works in Chrome and Safari, but not in FF 43.0.2. Firefox ignores the'scrollTop': $target.offset().top -100 line and scrolls directly to the anchor instead. I'm pretty new to programming, so any improvements on the code structure are also appreciated. Thanks!

    $('a[href^="#"]').on('click',function(e) {
e.preventDefault();

var target = this.hash;
var $target = $(target);

if ($(window).width() < 769) {
    $('html, body').stop().animate({
        'scrollTop': $target.offset().top -100
    }, 700, 'swing', function () {
        window.location.hash = target;
    });
    // Dropdown Menu Logic
        $('#nav-icon').toggleClass('open');
        $('#nav-mobile ul').slideToggle();
    }
    else {
        $('html, body').stop().animate({
        'scrollTop': $target.offset().top -150
    }, 700, 'swing', function () {
        window.location.hash = target;
    });
    // Dropdown Menu Logic
        $('#nav-icon').toggleClass('open');
        $('#nav-mobile ul').slideToggle();
    }
}); 

Answer 1

The code works fine but when you change the window.location after the animation is over, Firefox "jumps" to the corresponding anchor. This is actually the desired behavior.

To avoid this artifact, use history.pushState instead and fallback to location.hash on unsupported browsers :)

if(history.pushState){
    history.pushState(null, null, target);
}else{
    location.hash = target;
}

An example: http://codepen.io/victmo/pen/dGNvay

Cheers