Animate scroll to anchor on hash links (jQuery)

scrollToHash.js

var offset = offset || 0;
$('a[href*=#]').on('click', function (event) {
    event.preventDefault();
    // create a dummy element on current scroll position so we can write hash to document.location without scrolling immediately
    $('body').prepend('<div style="position: absolute;top:' + window.scrollY + 'px" id="' + this.hash.substr(1) + '" class="scroll-placeholder"></div>');
    document.location.hash = this.hash.substr(1);
    $(this.hash + '.scroll-placeholder').remove();
    // animate scroll
    $('html,body').animate({scrollTop: $(this.hash).offset().top + offset}, 500);
});