I ran into a problem when creating a scroll for headlines.

I looked at the element code, the code swears at the element "..offset().top"

$(function() {

    var header = $("header"),
        introH = $("#intro").innerHeight(),
        scrollOffset = $(window).scrollTop()

    // scroll
    checkScroll(scrollOffset)

    $(window).on("scroll", function() {
        scrollOffset = $(this).scrollTop()
        checkScroll(scrollOffset)

    })


    function checkScroll() {

        if (scrollOffset >= introH) {
            header.addClass("fixed")
        } else {
            header.removeClass("fixed")
        }
    }

    // scroll keys
    $("[data-scroll]").on("click", function(event) {
        event.preventDefault();

        var
            blockId = $(this).data("scroll"),
            blockOffset = $(blockId).offset().top            /* This line */


        $("html, body").animate({
            scrollTop: blockOffset
        }, 500)
    })

})

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