column chart (general update pattern)

forked from areologist's block: axes and margins

forked from areologist's block: axes and margins - responsive

forked from areologist's block: column chart

<!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-color: #f6fafc;
      border: 1px solid #333;
    }
    .bar {
      fill: steelblue;
      opacity: 0.7;
    }
    .bar:hover {
      opacity: 1;
    }
    .tick text {
      font-size: 10px;
    }
  </style>
</head>
<body>
  <div class="chart"></div>

<button onclick="changeSubject('math')">math</button>
  <button onclick="changeSubject('science')">science</button>
  <button onclick="changeSubject('language')">language</button>

const data = [
      {name: 'Alice', math: 37,   science: 52,   language: 54},
      {name: 'Billy', math: null, science: 34,   language: 95},
      {name: 'Cindy', math: 86,   science: 48,   language: null},
      {name: 'David', math: 44,   science: null, language: 75},
      {name: 'Emily', math: 59,   science: 43,   language: 29}
    ];

const 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 + ')');
    
    const xScale = d3.scaleBand()
    	.padding(0.2)
    	.domain(data.map(d => d.name))
    	.range([0, width]);

const yScale = d3.scaleLinear()
    	.domain([0, 100])
    	.range([height, 0]);

const yAxis = d3.axisLeft(yScale)
    	.ticks(10);

// add the axis by passing it into d3.call (and wrap it in a <g>)
    const yAxisElement = svg.append('g')
      .call(yAxis);

const xAxis = d3.axisBottom(xScale);

svg.append('g')
    	.attr('transform', `translate(0, ${height})`)
      .call(xAxis)
    	.selectAll('text')
    	.style('text-anchor', 'end')
    	.attr('transform', 'rotate(-45)');

function render(subject = 'math') {
      const speed = 500;
      const t = d3.transition()
      	.duration(speed)
      	.ease(d3.easeCubicOut);

const 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])])
      	.nice();

yAxisElement.transition()
      	.delay(speed)
      	.call(d3.axisLeft(yScale));

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

render();
    
    function changeSubject(subject) {
      render(subject);
    }

///

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