this.offset is not a function within a click function

Question

The error is that _this.offset is not a function. I logged this to the console and it was the <li> element I clicked on, so I am confused why this would not work.

 $('.item').click(function(e) { var _this = this; var topx = _this.offset().top; var leftx = _this.offset().left; var moveArea = $('#replace').offset().top; var moveLeft = $('#replace').offset().left; var moveUp = topx - moveArea - 50; _this.css('position', 'absolute').css('top', moveUp).css('zIndex', 50).css('left', leftx); _this.animate({ top: -50, left: moveLeft }, 300) });

 #replace { height: 50px; width: 100px; background-color: green; } #list { height: 200px; overflow-y: scroll; } .item { height: 50px; width: 100px; background-color: blue; }

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.2/jquery.min.js"></script> <div id="replace"> Replace this </div> <ul id="list"> <li class="item">TEST</li> <li class="item">TEST</li> <li class="item">TEST</li> </ul>

I also want to create an animation such that the item I click in the list moves up to replace the green "Replace this" box, if someone could help with that too.

I created a jsfiddle to show the error: https://jsfiddle.net/v5fjjwmj/2/

Answer 1

this (and hence _this ) inside your event handler refers to a DOMElement which doesn't have the offset() method as that's part of jQuery. To fix this you can create a jQuery object using $(this) :

$('.item').click(function(e) {
    var $this = $(this);
    var topx = $this.offset().top;
    var leftx = $this.offset().left;
    var moveArea = $('#replace').offset().top;
    var moveLeft = $('#replace').offset().left;
    var moveUp = topx - moveArea - 50;

    $this.css({
        'position': 'absolute',
        'top': moveUp,
        'zIndex': 50,
        'left': leftx
    }).animate({
        top: -50,
        left: moveLeft
    }, 300)
});

Also note the use of the object provided to a single css() call over multiple calls to the same method.

Answer 2

Replace these two lines:

var topx = _this.offset().top;
var leftx = _this.offset().left;

with:

var topx = _this.offsetTop;
var leftx = _this.offsetLeft;

As .offset() is a jquery function and _this is a DOM element.

---

Also for your .css line you have to wrap _this in $(...) again because _this is a DOM element and **not a jQuery object.