D3 Examples - Testing size of array

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<!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)
​
    var h = 3;
    var a = [1,2,4];
    
    if(! a.length || a.length > h) {
      a = new Array(h);
    }
    if(a.length < h) {
      a.push(1);
    } else {
      a[h-1] = 3;
    }
    
    
    svg.append("text")
      .text(a)
      .attr("y", 200)
      .attr("x", 120)
      .style("font-size", 36)
      .style("font-family", "monospace")
​
  </script>
</body>
​
    