d3 drag reset with multiple groups

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v5.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>

dock.append("circle")
      .attr("cx", (d, i) => circleRadius * (2 * i + 1))
      .attr("cy", circleRadius)
      .attr("r", circleRadius)
      .style("stroke", "none")
      .style("fill", "palegoldenrod");

dock.append("text")
      .attr("x", (d, i) => circleRadius * (2 * i + 1))
      .attr("y", circleRadius)
      .attr("text-anchor", "middle")
      .style("fill", "white")
      .text((d, i) => variables[i]);
    
    const draggablesGroup = svg.append('g')
    	.attr('id', 'draggables');
    
    const draggables = draggablesGroup.selectAll('g')
      .data(variables)
      .enter().append("g")
      .datum(function(d,i) {
     		return "translate("+[circleRadius * (2 * i + 1),circleRadius]+")";
  		})
      .attr("transform", (d,i) => d)
      .attr("id", (d, i) => variables[i])
      .call(d3.drag()
          .on("start", dragStarted)
          .on("drag", dragged)
          .on("end", dragEnded));

draggables.append('circle')
      .attr("r", circleRadius)
      .style("stroke", "orange")
      .style("fill", "yellowgreen");

draggables.append("text")
       .attr("text-anchor", "middle")
       .style("fill", "white")
       .text((d, i) => variables[i]);
    
    svg.append('rect')
      .attr("x", 960/2)
      .attr("y", 0)
      .attr("width", 100)
      .attr("height", 500/2)
      .attr("fill-opacity", 0)
      .style("stroke", "#848276")
      .attr("id", "hitZone");
    
    // functions
    function dragStarted() {
      d3.select(this).raise();
  	}

function dragged() {
			d3.select(this).attr("transform","translate("+[d3.event.x,d3.event.y]+")")
  	}

function dragEnded() {
    d3.select(this).lower();
    let hit = d3.select(document.elementFromPoint(d3.event.sourceEvent.clientX, d3.event.sourceEvent.clientY)).attr("id");

if (hit == "hitZone") {
      inZone.push(this.id);
      if (inZone.length > 1) {
        let resetVar = inZone.shift();
        resetCircle(resetVar);
      }
    }
    
    d3.select(this).raise();
  }

function resetCircle(resetVar) {
    d3.select(`#${resetVar}`)
      .transition()
        .duration(1000)
        .style('opacity', 0)
      .transition()
        .duration(500)
        .attr("transform", (d,i) => d)
      .transition()
        .duration(1000)
        .style('opacity', 1);
  }
  </script>
</body>

https://d3js.org/d3.v5.min.js