jQuery - Add active class and remove active from other element on click

$(document).ready(function() {
    $(".tab").click(function () {
        if(!$(this).hasClass('active'))
        {
            $(".tab.active").removeClass("active");
            $(this).addClass("active");        
        }
    });
});

You can remove class active from all .tab and use $(this) to target current clicked .tab:

$(document).ready(function() {
    $(".tab").click(function () {
        $(".tab").removeClass("active");
        $(this).addClass("active");     
    });
});

Your code won't work because after removing class active from all .tab, you also add class active to all .tab again. So you need to use $(this) instead of $('.tab') to add the class active only to the clicked .tab anchor

Updated Fiddle

Try this one:

$(document).ready(function() {
    $(".tab").click(function () {
        $("this").addClass("active").siblings().removeClass("active");   
    });
});

Try this

$(document).ready(function() {
$(".tab").click(function () {
    $(".tab").removeClass("active");
    // $(".tab").addClass("active"); // instead of this do the below 
    $(this).addClass("active");   
});
});

when you are using $(".tab").addClass("active");, it targets all the elements with class name .tab. Instead when you use this it looks for the element which has an event, in your case the element which is clicked.

Hope this helps you.