How to use d3 with reactJS / nextJS? - reactjs

Question

I would like to add a d3 chart, following the tutorials but nothing happens at all. i'm actually not sure if useEffect() is at the good "timing", if I should use componentDidMount, or if it's just not the good way to add in the element... Seems like I'm missing something here!
import React from 'react';
import * as d3 from "d3";
import { useEffect } from 'react';
function drawChart() {
const data = [12, 5, 6, 6, 9, 10];
const h = 100;
const w = 100;
const svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h)
.style("margin-left", 100);
svg.selectAll("rect")
.data(data)
.enter()
.append("rect")
.attr("x", (d, i) => i * 70)
.attr("y", (d, i) => h - 10 * d)
.attr("width", 65)
.attr("height", (d, i) => d * 10)
.attr("fill", "green")
}
const chart: React.FunctionComponent = () => {
useEffect(() => {
drawChart();
}, []);
return (
<div>
</div>
);
};
export default chart;

Answer 1

What can be a source of bugs in this example is that d3 is appending the SVG to the body, which is completely outside of the React DOM.
A better approach could be to add the SVG in the JSX, and use the reference (useRef in hooks) to tell D3 where the chart must be rendered:
import * as React from "react";
import * as d3 from "d3";
function drawChart(svgRef: React.RefObject<SVGSVGElement>) {
const data = [12, 5, 6, 6, 9, 10];
const h = 120;
const w = 250;
const svg = d3.select(svgRef.current);
svg
.attr("width", w)
.attr("height", h)
.style("margin-top", 50)
.style("margin-left", 50);
svg
.selectAll("rect")
.data(data)
.enter()
.append("rect")
.attr("x", (d, i) => i * 40)
.attr("y", (d, i) => h - 10 * d)
.attr("width", 20)
.attr("height", (d, i) => d * 10)
.attr("fill", "steelblue");
}
const Chart: React.FunctionComponent = () => {
const svg = React.useRef<SVGSVGElement>(null);
React.useEffect(() => {
drawChart(svg);
}, [svg]);
return (
<div id="chart">
<svg ref={svg} />
</div>
);
};
export default Chart;
Here is a codePen for the example