How to get the value of CSS style using jQuery

Question

I doubt css understands left by itself. You need to use it specifying position. You are using .css() correctly

position: relative/absolute/whatever;
left: 900px;

heres a fiddle of it working

https://jsfiddle.net/gFLZe/

and without the position here’s what you get

https://jsfiddle.net/gkkm5/

Change your if statement to be like this – with quotes around -900px

var n = $("items").css("left");

if(n == '-900px'){
    $(".items span").fadeOut("slow");
}

https://jsfiddle.net/gFLZe/1/