Selection area with the mouse?

var draggingMouse = false;
var leftMouseDrag, topMouseDrag;
$(document).on("mousedown mouseup", "#cloud_main_page", function(e){	
	if (e.type == "mousedown") {
		draggingMouse = true;
		var offset = $(this).offset();
		
		leftMouseDrag = e.pageX - offset.left;
		topMouseDrag = e.pageY - offset.top
		
		$("#cloud_main_page .cloud_mouse_selection").css({"top": topMouseDrag, "left" : leftMouseDrag});
			
	} else{
		draggingMouse = false;	
		$("#cloud_main_page .cloud_mouse_selection").removeAttr("style");
	}
		
}).on("mousemove", "#cloud_main_page", function(e){
	if(draggingMouse){
		var offsetDrag = $("#cloud_main_page .cloud_mouse_selection").offset();
			
		var top = e.pageY - offsetDrag.top;
		var left = e.pageX - offsetDrag.left;
      
		var width = Math.abs(left);
		var height = Math.abs(top);
			
		$("#cloud_main_page .cloud_mouse_selection").css({"width": width, "height": height});
	}
});

#cloud_main_page{
  width:400px;
  height:400px;
  
  position:relative;
}
#cloud_main_page .cloud_mouse_selection{	
	position:absolute;
	
	background-color:rgba(6, 217, 160, 0.05);
	border: 1px solid rgba(6, 217, 160, 0.3);	
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script><divid="cloud_main_page">
  <div class="cloud_mouse_selection"></div>
</div>