events and ES6 arrow functions [UNLISTED]

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

<body>
  <script>
    // Feel free to change or delete any of the code you see in this editor!
    var svg = d3.select("body").append("svg")
      .attr("width", 960)
      .attr("height", 500)

// With regular functions I use _this_ to react to an event
    svg.selectAll('text')
      .data([1,2])
      .enter()
      .append("text")
      .text((d) => "hover me " + d)
      .attr("y", (d,i) => 110 + 50 * i)
      .attr("x", 120)
      .style("font-size", 36)
      .style("font-family", "monospace")
    .on('mousemove', function() {
      d3.select(this)
        .text(Math.random()).attr('fill', 'blue')
    } 
    );

// With arrow functions, _this_ is not available, and I need to add an id
    svg.selectAll('text')
      .data([1,2,3,4])
      .enter()
      .append("text")
      .attr('id', (d,i) => "data-" + i)
      .text((d) => "hover me " + d)
      .attr("y", (d,i) => 130 + 50 * i)
      .attr("x", 120)
      .style("font-size", 36)
      .style("font-family", "monospace")
    .on('mousemove', (d,i) => 
      svg.select("#data-" + i)
        .text(Math.random()).attr('fill', 'green')
    );

// d3.event.target to the rescue
    svg.selectAll('text')
      .data([1,2,3,4,5,6])
      .enter()
      .append("text")
      .text((d) => "hover me " + d)
      .attr("y", (d,i) => 150 + 50 * i)
      .attr("x", 120)
      .style("font-size", 36)
      .style("font-family", "monospace")
    .on('mousemove', () => d3.select(d3.event.target)
        .text(Math.random()).attr('fill', 'red')
       );

</script>
</body>

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