<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Vertical Bar Chart</title>
<script src="https://d3js.org/d3.v7.js"></script>
</head>
<body>
<script>
// Create svg and initial bars
const w = 400;
const h = 300;
const margin = {top: 25, right: 0, bottom: 25,
left: 25};
const innerWidth = w - margin.left - margin.right;
const innerHeight = h - margin.top - margin.bottom;
const svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
svg.append("rect")
.attr("x", 0)
.attr("y", 0)
.attr("width", w)
.attr("height", h)
.attr("fill", "lightblue");
const bardata = [300, 100, 150, 220, 70, 270];
const xScale = d3.scaleBand()
.domain(d3.range(bardata.length))
.range([0, innerWidth])
.paddingInner(.1);
const yScale = d3.scaleLinear()
.domain([0, d3.max(bardata)])
.range([innerHeight, 0])
const xAxis = d3.axisBottom()
.scale(xScale);
const yAxis = d3.axisLeft()
.scale(yScale);
const bars = svg.append("g")
.attr("id", "plot")
.attr("transform", `translate (${margin.left}, ${margin.top})`)
.selectAll("rect")
.data(bardata);
bars.enter().append("rect")
.attr("x", (d, i) => xScale(i))
.attr("y", d => yScale(d))
.attr("width", xScale.bandwidth())
.attr("height", d => innerHeight - yScale(d))
.attr("fill", "blue");
svg.append("g")
.attr("class", "xAxis")
.attr("transform", `translate (${margin.left}, ${h - margin.bottom})`)
.call(xAxis);
svg.append("g")
.attr("class", "yAxis")
.attr("transform", `translate (${margin.left}, ${margin.top})`)
.call(yAxis);
// General Update Pattern
function update(data) {
xScale.domain(d3.range(data.length));
yScale.domain([0, d3.max(data)]);
const bars = svg.select("#plot")
.selectAll("rect")
.data(data);
bars.enter().append("rect")
.merge(bars)
.attr("x", (d, i) => xScale(i))
.attr("y", d => yScale(d))
.attr("width", xScale.bandwidth())
.attr("height", d => innerHeight - yScale(d))
.attr("fill", "blue");
bars.exit().remove();
svg.select(".xAxis")
.call(xAxis);
svg.select(".yAxis")
.call(yAxis);
}
function add() {
var newvalue = Math.floor(Math.random()*400);
bardata.push(newvalue);
update(bardata);
}
function remove() {
bardata.pop();
update(bardata);
};
</script>
<p></p>
<button type="button" onclick="add()">Add bar</button>
<button type="button" onclick="remove()">Remove bar</button>
</body>
</html>