未捕获的TypeError：无法读取未定义的属性“ top”

Question

Trying to use a button to go to an anchor.

My JS code is:

    function scrollToAnchor(aid){
        var aTag = $("a[name='"+ aid +"']");
        $('html,body').animate({scrollTop: aTag.offset().top},'slow');
    }

    $("#AsGuest").click(function() {
       scrollToAnchor('FName_Ship');
    });

HTML button I'm using as the click:

 <input type="Submit" id="AsGuest" class="btn btn-orange" value="CONTINUE AS A GUEST" style="margin-top:5px;"/>

Area I'm going to upon click:

 <input type="text" id="FName_Ship" name="FName_Ship" value="James" onchange="$.ajax( { type: 'GET', dataType: 'json', url: 'dmiajaxsecure.aspx?request=updatedata&amp;fieldname=shipfname&amp;fieldvalue=' + this.value + '&amp;extra=' + rnd() } );" class="valid">

Answer 1

jQuery.offset() returns null when you it is called on an empty jQuery object. Check aTag.length before attempting to call .offset() method, most likely the anchor does not exist.

Answer 2

Replace the a tag by input , as it is the element you actually target.

function scrollToAnchor(aid){
    var inputTag = $("input[name='"+ aid +"']");
    $('html,body').animate({scrollTop: inputTag.offset().top},'slow');
}

$("#AsGuest").click(function() {
   scrollToAnchor('FName_Ship');
});