Call function on scroll only once

Question

I got a question regarding a function that will be called if the object is within my screen. But when the object is within my screen the function is been called and a alert

Answer 1

when the $test is within in you screen, remove the event listener.

$(window).on('scroll',function() {
    if (checkVisible($('#tester'))) {
       alert("Visible!!!")   
       $(window).off('scroll');
    } else {
    // do nothing
    }
});