Animate with the General Update Pattern in D3

<!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; }
    .chart {
      background: lightgray;
      border: 1px solid black;
    }
    rect {
      fill: steelblue;
    }
  </style>
</head>

<body>
  <div class="chart"></div>
  <button onclick="render('math')">Math</button>
  <button onclick="render('science')">Science</button>
  <button onclick="render('language')">Language</button>
  
  <script>
    var data = [
      {
        "name": "Alice",
        "math": 137,
        "science": 62,
        "language": 54
      },
      {
        "name": "Billy",
        "math": null,
        "science": 34,
        "language": 85
      },
      {
        "name": "Cindy",
        "math": 86,
        "science": 48,
        "language": null
      },
      {
        "name": "David",
        "math": 44,
        "science": null,
        "language": 65
      },
      {
        "name": "Emily",
        "math": 59,
        "science": 63,
        "language": 29
      }
    ]

// 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)

//     svg.append("text")
//       .text("Edit the code below to change me!")
//       .attr("y", 200)
//       .attr("x", 120)
//       .attr("font-size", 36)
//       .attr("font-family", "monospace")
    
    var margin = { top: 10, right: 25, bottom: 35, left: 20 }
    var width = 800 - margin.left - margin.right
    var height = 600 - margin.top - margin.bottom
    var svg = d3.select('.chart')
    	.append('svg')
        .attr('width', width + margin.left + margin.right)
        .attr('height', height + margin.top + margin.bottom)
        .call(responsivefy)
   		.append('g')
    		.attr('transform', `translate(${margin.left}, ${margin.top})`)
    	
    var xScale = d3.scaleBand()
    	.domain(data.map(d => d.name))
    	.range([0, width])
    	.padding(0.2)
    
    var xAxis = d3.axisBottom(xScale)
    svg.append('g')
    	.attr('transform', `translate(0, ${height})`)
    	.call(xAxis)
    
    var yScale = d3.scaleLinear()
    	.domain([0, 100])
    	.range([height, 0])
//     var yAxis = d3.axisLeft(yScale)
//     	.ticks(10)
    
    var yAxis = svg.append('g')
    	.attr('transform', `translate(${margin.left}, ${margin.top})`)
    	.call(d3.axisLeft(yScale))
    
    function render (subject = 'math') {
      var t = d3.transition().duration(500);

var update = svg.selectAll('rect')
        .data(data.filter(d => d[subject]), d => d.name);

update.exit()
        .transition(t)
        .attr('y', height)
        .attr('height', 0)
        .remove();
			
      yScale.domain([0, d3.max(data, d => d[subject])])
      yAxis
      	.transition(t)
      	.delay(1000)
      	.call(d3.axisLeft(yScale))
      
      update
        .transition(t)
        .delay(1000)
        .attr('y', d => yScale(d[subject]))
        .attr('height', d => height - yScale(d[subject]));

update
        .enter()
        .append('rect')
        .attr('y', height)
        .attr('height', 0)
        .attr('x', d => xScale(d.name))
        .attr('width', d => xScale.bandwidth())
        .transition(t)
        .delay(update.exit().size() ? 2000 : 0)
        .attr('y', d => yScale(d[subject]))
        .attr('height', d => height - yScale(d[subject]));
    }

render();
    
		function responsivefy(svg) {
      // get container + svg aspect ratio
      var container = d3.select(svg.node().parentNode),
          width = parseInt(svg.style("width")),
          height = parseInt(svg.style("height")),
          aspect = width / height;

// add viewBox and preserveAspectRatio properties,
      // and call resize so that svg resizes on inital page load
      svg.attr("viewBox", "0 0 " + width + " " + height)
          .attr("preserveAspectRatio", "xMinYMid")
          .call(resize);

// to register multiple listeners for same event type,
      // you need to add namespace, i.e., 'click.foo'
      // necessary if you call invoke this function for multiple svgs
      // api docs: https://github.com/mbostock/d3/wiki/Selections#on
      d3.select(window).on("resize." + container.attr("id"), resize);

// get width of container and resize svg to fit it
      function resize() {
          var targetWidth = parseInt(container.style("width"));
          svg.attr("width", targetWidth);
          svg.attr("height", Math.round(targetWidth / aspect));
      }
    }
  </script>
</body>

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