update endpoint on mousemove

<!DOCTYPE html>



 <html class="no-js"> 
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>Update End Point on Mousemove</title>
    <meta name="description" content="">
    <meta name="viewport" content="width=device-width, initial-scale=1">
  </head>
  <body>
    
    
    <div id="d3-drawing-area"></div>

var line = svg.append('line')
        .attr('x1', 100)
        .attr('y1', 100)
        .attr('x2', 200)
        .attr('y2', 200)
        .style('stroke', 'blue')
        .style('stroke-width', 2);

// update endpoint on mousemove over svg
      svg.on('mousemove', function() {
        // get mouse position relative to "this" svg
        var mousePosition = d3.mouse(this);
        // use it to update endpoint (x2, y2)
        line
          .attr('x2', mousePosition[0])
          .attr('y2', mousePosition[1]);
      });
    </script>

</body>
</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/4.6.0/d3.min.js