This chart is based on mbostock's block: Line Chart
it uses a json file storing year values and population values. The chart employs conventional margins and a number of D3 features:
forked from alandunning's block: Line Chart with Circle Tooltip D3 V4
xxxxxxxxxx<meta charset="utf-8"><head> <link href="https://fonts.googleapis.com/css?family=Fira+Sans:300,300i,400,500,700" rel="stylesheet"></head><style>body { background-color: #F1F3F3; font-family: 'Fira Sans', sans-serif;} text { font-family: 'Fira Sans', sans-serif; font-weight: 500; font-size: 15px; color: #081F2C;}.axis path,.axis line { fill: none; stroke: #D4D8DA; stroke-width: 2px; shape-rendering: crispEdges;} .axis-title{ fill: #5B6770; letter-spacing: 1px;}.line { fill: none; stroke: #6F257F; stroke-width: 5px;}.overlay { fill: none; pointer-events: all;}.focus circle { fill: #F1F3F3; stroke: #6F257F; stroke-width: 5px;} .hover-line { stroke: #6F257F; stroke-width: 2px; stroke-dasharray: 2,4;}</style><body><svg width="960" height="500"></svg><script src="https://d3js.org/d3.v4.min.js"></script><script>var svg = d3.select("svg"), margin = {top: 20, right: 20, bottom: 30, left: 40}, width = +svg.attr("width") - margin.left - margin.right, height = +svg.attr("height") - margin.top - margin.bottom;var parseTime = d3.timeParse("%Y") bisectDate = d3.bisector(function(d) { return d.year; }).left;var x = d3.scaleTime().range([0, width]);var y = d3.scaleLinear().range([height, 0]);var line = d3.line() .x(function(d) { return x(d.year); }) .y(function(d) { return y(d.value); });var g = svg.append("g") .attr("transform", "translate(" + margin.left + "," + margin.top + ")");d3.json("data.json", function(error, data) { if (error) throw error; data.forEach(function(d) { d.year = parseTime(d.year); d.value = +d.value; }); x.domain(d3.extent(data, function(d) { return d.year; })); y.domain([d3.min(data, function(d) { return d.value; }) / 1.005, d3.max(data, function(d) { return d.value; }) * 1.005]); g.append("g") .attr("class", "axis axis--x") .attr("transform", "translate(0," + height + ")") .call(d3.axisBottom(x)); g.append("g") .attr("class", "axis axis--y") .call(d3.axisLeft(y).ticks(6).tickFormat(function(d) { return parseInt(d / 1000) + "k"; })) .append("text") .attr("class", "axis-title") .attr("transform", "rotate(-90)") .attr("y", 6) .attr("dy", ".71em") .style("text-anchor", "end") .text("Population"); g.append("path") .datum(data) .attr("class", "line") .attr("d", line); var focus = g.append("g") .attr("class", "focus") .style("display", "none"); focus.append("line") .attr("class", "x-hover-line hover-line") .attr("y1", 0) .attr("y2", height); focus.append("line") .attr("class", "y-hover-line hover-line") .attr("x1", width) .attr("x2", width); focus.append("circle") .attr("r", 6); focus.append("text") .attr("x", 15) .attr("dy", ".31em"); svg.append("rect") .attr("transform", "translate(" + margin.left + "," + margin.top + ")") .attr("class", "overlay") .attr("width", width) .attr("height", height) .on("mouseover", function() { focus.style("display", null); }) .on("mouseout", function() { focus.style("display", "none"); }) .on("mousemove", mousemove); function mousemove() { var x0 = x.invert(d3.mouse(this)[0]), i = bisectDate(data, x0, 1), d0 = data[i - 1], d1 = data[i], d = x0 - d0.year > d1.year - x0 ? d1 : d0; focus.attr("transform", "translate(" + x(d.year) + "," + y(d.value) + ")"); focus.select("text").text(function() { return d.value; }); focus.select(".x-hover-line").attr("y2", height - y(d.value)); focus.select(".y-hover-line").attr("x2", width + width); }});</script> https://d3js.org/d3.v4.min.js