JSFiddle - React, Tailwind, and code Playground

HTML

<div class = gamer> </div>
<div class = blok> </div>

CSS

.gamer {
	
position: absolute;

top: 50%;
	
width: 50px;
height: 50px;
background-color: red;	
		
}

.blok{
	
position: absolute;

top: 50%;
left: 50%;	
width: 50px;
height: 50px;
background-color: green;	
		
}

JavaScript

function Game (time, klas) {
	
	this.anim = function () {
        $("."+klas).animate({"top":"90%"},  { duration: time  });
    $("."+klas).animate({"top":"0%"}, { duration: time  });
	                        }
}
	
	
	var kub1 = new Game (2000,"blok");

setInterval(kub1.anim , 1000);


	
	
var redTop = $(".gamer").offset().top;
var redDown = $(".gamer").offset().top - 50;

var redRight = $(".gamer").offset().left + 50;
var redLeft = $(".gamer").offset().left;
		
		
var greenRight = $(".blok").offset().left + 50;
var greenLeft = $(".blok").offset().left;

var greenTop = $(".blok").offset().top;
var greenDown = $(".blok").offset().top - 50;



//УСЛОВИЕ  УСЛОВИЕ  УСЛОВИЕ  УСЛОВИЕ  УСЛОВИЕ

if (redTop >= greenDown && redDown <=greenTop)	{
;
	$(".blok").append("ALERT");
	alert("ALERT");
	
	
	}