d3intro_ex19

Intro d3js

### Example19 - enter()

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Intro d3js examples</title>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
    <style>
      body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
      p.update:hover {
        cursor: pointer;
      }
    </style>
  </head>
  <body>
    <h1>Intro d3js - example19</h1>
    <p class="update">click this text to add new data.</p>
    
    <script type="text/javascript">
    	//Width and height
      var w = 600;
      var h = 250;
      var offset = 10;
      
      var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, 15, 13,
              11, 12, 15, 20, 18, 17, 16, 18, 23, 25 ];
      
      var xScale = d3.scale.ordinal()
              .domain(d3.range(dataset.length))
              .rangeRoundBands([0, w], 0.05);

var yScale = d3.scale.linear()
              .domain([0, d3.max(dataset)])
              .range([h, 0]);
      
      //Create SVG element
      var svg = d3.select("body")
            .append("svg")
            .attr("width", w)
            .attr("height", h);

//Create bars
      svg.selectAll("rect")
         .data(dataset)
         .enter()
         .append("rect")
         .attr("x", function(d, i) {
             return xScale(i);
         })
         .attr("y", function(d) {
             return yScale(d);
         })
         .attr("width", xScale.rangeBand())
         .attr("height", function(d) {
             return h - yScale(d);
         })
         .attr("fill", function(d) {
          return "rgb(0, 0, " + (d * 10) + ")";
         });

//Create labels
      svg.selectAll("text")
         .data(dataset)
         .enter()
         .append("text")
         .text(function(d) {
             return d;
         })
         .attr("text-anchor", "middle")
         .attr("x", function(d, i) {
             return xScale(i) + xScale.rangeBand() / 2;
         })
         .attr("y", function(d) {
             return yScale(d) + offset;
         })
         .attr("font-family", "sans-serif")
         .attr("font-size", "11px")
         .attr("fill", "white");

//On click, update with new data      
      d3.select("p.update")
        .on("click", function() {

//Add one new value to dataset
          var maxValue = 25;
          var newNumber = Math.floor(Math.random() * maxValue);
          dataset.push(newNumber); //Add new number to array
          
          //Update scale domains
          xScale.domain(d3.range(dataset.length));
          yScale.domain([0, d3.max(dataset)]);

var bars = svg.selectAll("rect") //Select all bars
                        .data(dataset); //Re-bind data
          //'bars' is now the update selection

//Enter…
          bars.enter() //Enter selection (a subset of the update selection)
            .append("rect") //Creates a new rect
            .attr("x", w)
            .attr("y", function(d) { 
              return yScale(d);
            })
            .attr("width", xScale.rangeBand()) 
            .attr("height", function(d) { 
              return h - yScale(d);
            })
            .attr("fill", function(d) {
              return "rgb(0, 0, " + (d * 10) + ")";
            });

//Update…
          bars.transition() 
            .duration(500)
            .attr("x", function(d, i) {
              return xScale(i);
            })
            .attr("y", function(d) {
              return yScale(d);
            })
            .attr("width", xScale.rangeBand())
            .attr("height", function(d) {
              return h - yScale(d);
            });

//Update all labels
          labels = svg.selectAll("text")
             .data(dataset);
             
          //Enter…
          labels.enter()
                .append("text")
                .text(function(d) {
                  return d.value;
                })
                .attr("text-anchor", "middle")
                .attr("x", w)
                .attr("y", function(d) {
                  return yScale(d) + offset;
                })            
                .attr("font-family", "sans-serif")
                .attr("font-size", "11px")
                .attr("fill", "white");
          
          //Update      
          labels.transition()
                .duration(500)
                .text(function(d) {
                    return d;
                })
                .attr("x", function(d, i) {
                 return xScale(i) + xScale.rangeBand() / 2;
                })
                .attr("y", function(d) {
                 return yScale(d) + offset;
                });
                     
        });
      </script>
  </body>
</html>

https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js