[D3] Basic Interactivity with D3 v4

Data visualizations are a lot more interesting when they’re interactive. Whether it’s clicks, roll overs, or drags, it makes things more compelling, and D3 is up to the task. This lesson demonstrates how to implement basic interactions and shows how D3 can do things vanilla CSS can’t.

var scores = [
  { name: 'Alice', score: 96 },
  { name: 'Billy', score: 83 },
  { name: 'Cindy', score: 91 },
  { name: 'David', score: 96 },
  { name: 'Emily', score: 88 }
];

const bars = d3.select('.chart')
    .append('svg')
        .attr('width', 300)
        .attr('height', 300)
        .style('background', 'white')
    .selectAll('g')
    .data(scores)
    .enter()
        .append('g')
        .attr('transform', (d, i) => 'translate(0, ' + i * 33 + ')');


bars.append('rect')
    .attr('width', d => d.score)
    .attr('class', 'bar')
    .on('mouseover', function(d, i, elements) {
        // transform the hover item to scale 1.1
        d3.select(this).classed('barOn', true);

        // set not hover elements to opacity 0.8
        d3.selectAll(elements)
            .filter(':not(:hover)')
            .style('opacity', 0.6);
    })
    .on('mouseout', function(d, i, elements) {
        d3.select(this).classed('barOn', false);
        d3.selectAll(elements)
            .style('opacity', 1);
    });

bars.append('text')
    .text(d => d.name)  
    .attr('y', 20)