Line chart angles smoother using D3 - d3.js

Question

I am trying to make the angles on this chart smoother, D3.js is being used and I already tried to apply a few ideas as solution, like adding .interpolate("basis") on the code, but for some reason the chart disappear when I do it.
Do you have any clue on what am I doing wrong? The dots are draggable and this is the intended behavior.
Here's a sample to the code: https://codepen.io/A8-XPs/pen/ePWRxZ?editors=1010
HTML:
<svg width="500" height="350"></svg>
JS:
var svg = d3.select("svg"),
margin = {top: 20, right: 20, bottom: 30, left: 50},
width = +svg.attr("width") - margin.left - margin.right,
height = +svg.attr("height") - margin.top - margin.bottom;
let points = d3.range(1, 10).map(function(i) {
return [i * width / 10, 50 + Math.random() * (height - 100)];
});
var x = d3.scaleLinear()
.rangeRound([0, width]);
var y = d3.scaleLinear()
.rangeRound([height, 0]);
var xAxis = d3.axisBottom(x),
yAxis = d3.axisLeft(y);
var line = d3.line()
.x(function(d) { return x(d[0]); })
.y(function(d) { return y(d[1]); });
let drag = d3.drag()
.on('start', dragstarted)
.on('drag', dragged)
.on('end', dragended);
svg.append('rect')
.attr('class', 'zoom')
.attr('cursor', 'move')
.attr('fill', 'none')
.attr('pointer-events', 'all')
.attr('width', width)
.attr('height', height)
.attr('transform', 'translate(' + margin.left + ',' + margin.top + ')')
var focus = svg.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
x.domain(d3.extent(points, function(d) { return d[0]; }));
y.domain(d3.extent(points, function(d) { return d[1]; }));
focus.append("path")
.datum(points)
.attr("fill", "none")
.attr("stroke", "steelblue")
.attr("stroke-linejoin", "round")
.attr("stroke-linecap", "round")
.attr("stroke-width", 1.5)
.attr("d", line);
focus.selectAll('circle')
.data(points)
.enter()
.append('circle')
.attr('r', 5.0)
.attr('cx', function(d) { return x(d[0]); })
.attr('cy', function(d) { return y(d[1]); })
.style('cursor', 'pointer')
.style('fill', 'steelblue');
focus.selectAll('circle')
.call(drag);
focus.append('g')
.attr('class', 'axis axis--x')
.attr('transform', 'translate(0,' + height + ')')
.call(xAxis);
focus.append('g')
.attr('class', 'axis axis--y')
.call(yAxis);
function dragstarted(d) {
d3.select(this).raise().classed('active', true);
}
function dragged(d) {
d[0] = x.invert(d3.event.x);
d[1] = y.invert(d3.event.y);
d3.select(this)
.attr('cx', x(d[0]))
.attr('cy', y(d[1]))
focus.select('path').attr('d', line);
}
function dragended(d) {
d3.select(this).classed('active', false);
}
Thank you!

Answer 1

To get basic interpolation use
var line = d3.line()
.x(function(d) { return x(d[0]); })
.y(function(d) { return y(d[1]); })
.curve(d3.curveBasis);
or
.curve(d3.curveCatmullRom.alpha(0.5))