What is the meaning of the “t” in the code and what does t(window) mean?

Question

I am trying to learn jquery/javascript by looking at the source code of some websites. I am a bit unsure about the syntax used there:

!function(t) {
    "use strict";

        function e() {
        var e = parseInt(t(window).scrollTop()),
            n = 10;
        e > n ? a.addClass("new-class") : (a.removeClass("new-class"), t(".sclass").removeClass("fclass"))
    }
    //...more codes...
}(jQuery),

I just don't really get what exactly is the meaning of that t there. Is it "this" or just any event object? and what does t(window) means? I thought it should be something like t.window? Since t is not a function.

Thanks! Saldtch

Answer 1

t is a reference to the jQuery object within the scope of that function. Notice how the function is called:

!function (t) {
    // "t" is the jQuery object
}(jQuery);

The function is defined and then immediately invoked with the parameter jQuery . So when the function is invoked, that parameter being passed is stored in the variable t . You could name it anything, really:

!function (foo) {
    // "foo" is the jQuery object
}(jQuery);

Answer 2

The function is defined inline, so it doesn't have a name, and immediatley gets called with param jQuery. "t" is the formal parameter of the inline function, which gets resolved with the concrete parameter "jQuery".

Shortly, variable t refers to the jQuery object (or whatever jQuery variable holds).

Answer 3

That's equivalent to:

function x(t) {
    //code in here
}

x(jQuery);

Therefore t is a local reference in the function to jQuery .

And, t(window) is equivalent to jQuery(window) ... and by extension $(window) .

Answer 4

Insert this code in the function e() :

console.log(t === jQuery);

You will assert that t is jQuery alias indeed in that function.

Answer 5

As already mentioned above, t equals to the jquery object in this case. t(window) means, wrap the window object with the jquery object, so after wrapping it, i can call jquery methods on it. I'm sure you are already familiar with jquery's $(selector) method, which does the same (fair enough).

So, $('#product') should get the DOM element with id "product" and wrap it inside a jquery object.

Example :

var myProduct = document.querySelector('#product');
myProduct.attr('id'); // error, myProduct doesn't have method attr() because it is not a jquery "instance"
$(myProduct).attr(id); // product, we wrapped the item in a jquery object

Since jquery is named as t in your example, t(window) is wrapping the window object in jquery. The window object normally doesn't have a scrollTop() method defined on it.