Is it possible to get the id of the class instance that caused an if statement to return true?

For instance, if I have three divs, each with the class of "sectionBox" and the ids of "one", "two" and "three", respectively, how would I detect and return the id of one that leaves the page after scrolling? I would guess I should use a "this" keyword, but I'm unclear how to use one without an event handler using jQuery.

Essentially what I'm trying to do is take this code and consolidate it so I don't have to use it three or four more times.

jQuery

$(document).scroll(function(){
        var threeQuartersBox = $(".sectionBox").height()*.75;
        if($(window).scrollTop() < threeQuartersBox){
        $("body, #colorBar, #navBarWrapper").addClass("myBlue", 200).removeClass("myRed", 200);
        console.log("Something happened.");
        }else if($(window).scrollTop() > threeQuartersBox){
        $("body, #colorBar, #navBarWrapper").addClass("myRed", 200).removeClass("myBlue", 200);
        console.log("Something NEW happened.")
        }
        //console.log($(window).scrollTop());
        //console.log($(".sectionBox").height());
    });//endScrollFunction
})()