scatter

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <script src="data.js"></script>
  <script src="data2.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <script>
    const width = 960;
    const height = 500;
    const margin = { left: 40, right: 20, top: 20, bottom: 20};
    var svg = d3.select('body').append('svg')
      .attr('width', width)
      .attr('height', height)
    
    const xScale = d3.scaleLinear()
    	.range([margin.left, width - margin.right])
    
    const yScale = d3.scaleLinear()
    	.range([height - margin.bottom, margin.top ])
    
    const x = svg.append('g')
      .attr('transform', `translate(0, ${margin.top})`);
    const y = svg.append('g')
      .attr('transform', `translate(${margin.left}, 0)`);
    
    const graph = svg.append('g')
    const redLine = svg.append('line');
    
    const createGraph = data => {
      const t = d3.transition().duration(3000);
      xScale.domain([
        d3.min(data, d => d.value[0].x)-3000,
        d3.max(data, d => d.value[0].x)+3000
      ]);
      yScale.domain([
        d3.min(data, d => d.value[0].y)-1,
        d3.max(data, d => d.value[0].y)+1
      ]);

let scatter = graph.selectAll('circle')
        .data(data, (d,i) => i);

const enter = scatter.enter().append('circle')
        .attr('r', 0);

scatter.exit()
      	.transition(t)
        .attr('r', 0)
      	.remove()
      
      scatter = enter.merge(scatter)
        .attr('fill', d => d.value[0].y > 0 ? 'green' : 'red')
        .transition(t)
      	.attr('cx', d => xScale(d.value[0].x))
        .attr('cy', d => yScale(d.value[0].y))
        .attr('r', 5);

redLine
        .attr('x1', xScale(xScale.domain()[0]))
        .attr('x2', xScale(xScale.domain()[1]))
        .attr('y1', yScale(0))
        .attr('y2', yScale(0))
        .attr('stroke-width', 3)
        .attr('stroke', 'red')
    
    
    const xAxis = d3.axisTop().scale(xScale);
    const yAxis = d3.axisLeft().scale(yScale);
    
    x.call(xAxis);
		y.call(yAxis);
      
    }
    createGraph(data2)
    setTimeout(() => {
      data2.forEach(d => {
        d.x = +d.x;
        d.y = +d.y;
      });
    	createGraph(data1);
      
    }, 3000)
  </script>
</body>

https://d3js.org/d3.v4.min.js