Develop Reference

D3.js rect no display on chart

I started the D3.js challenge on FreeCodeCamp, the problem is that I solved it with the chart but it only gives me a display on the rectum, only one with the width and height that it I put, I'll show the code below.
The entire code on
<script>
//set d3
var w = 1000, h = 500;
var padding = 50;
var svg = d3.select('body')
.append('svg')
.attr('width', w)
.attr('height', h)
//title
svg.append('text')
.attr('x', w / 2)
.attr('y', 50)
.text('United States GDP')
fetch('https://raw.githubusercontent.com/freeCodeCamp/ProjectReferenceData/master/GDP-data.json')
.then((result)=>result.json())
.then((data)=>{
var the_data = data['data']
//get vals
var get_max = d3.max(data['data'])
var get_mix = d3.min(data['data'])
//for x
var max_x = Number(get_max[0].split('-')[0])
var min_x = Number(get_mix[0].split('-')[0])
//for y
var max_y = get_max[1]
var min_y = get_mix[1]
var xScale = d3.scaleLinear()
.domain([min_x, max_x])
.range([padding, w-padding])
var yScale = d3.scaleLinear()
.domain([min_y, max_y])
.range([h-padding, padding])
//the_chars
for(var i in the_data){
var get_year = Number(the_data[i][0].split('-')[0])
the_data[i][0] = get_year
}
svg.selectAll('rect')
.data(the_data)
.enter()
.append('rect')
.attr("x", (d) => { xScale(d[0]) })
.attr('y', (d)=>{ yScale(d[1]) })
.attr("width", 200)
.attr("height", 20)
//axis
const xAxis = d3.axisBottom(xScale);
const yAxis = d3.axisLeft(yScale);
//display axis
svg.append("g")
.attr("transform", "translate(0," + (h - padding) + ")")
.call(xAxis);
svg.append('g')
.attr('transform', 'translate(' + padding + ', 0)')
.call(yAxis)
})
Now, what I need to do to display the charts!
I mention that the script tags are embedded in the body

Problem: Arrow functions without a return value. Solution: Instead use an explicit or an implicit return.
.attr("x", (d) => { xScale(d[0]) }) // returns undefined
.attr("x", (d) => xScale(d[0])) // implicit return
.attr("x", (d) => { return xScale(d[0]) }) // explicit return
Problem: Fixed height value. Solution Evaluate the height of each based on the GDP value (d[1]) instead.
.attr('height', 20) // fixed height
.attr('height', d => yScale(min_y) - yScale(d[1]))
// subtract from min range to account for padding and inverted y coordinates in SVG
Full solution in this codepen

Why is it showing only one rect for the last value of each year in my d3js bar chart?

Trying to build a bar chart and, I don't know why, it's only showing the last value for each year and not all the values in both arrays, and that's what I thought that it was supposed to happen. How can I fix that?
let url = "https://raw.githubusercontent.com/freeCodeCamp/ProjectReferenceData/master/GDP-data.json";
const padding = 50;
const height = 460;
const width = 940;
var svg = d3.select('body')
.append('svg')
.attr('width', width)
.attr('height', height);
var arr = [];
var years = [];
d3.json(url, function(data) {
for (let i = 0; i < data.data.length; i++) {
arr[i] = data.data[i];
years[i] = parseInt(data.data[i][0].slice(0,4));
}
const yScale = d3.scaleLinear()
.domain([0, d3.max(arr, (d) => d[1])])
.range([height - padding, padding]);
const xScale = d3.scaleLinear()
.domain([d3.min(years, d => d), d3.max(years, (d) => d)])
.range([padding, width - padding]);
let bandScale = d3.scaleBand().domain(years, d => d).range([padding, width - padding]);
const xAxis = d3.axisBottom(bandScale)
const yAxis = d3.axisLeft(yScale);
svg.append("g")
.attr("transform", "translate(0," + (height - padding) + ")")
.call(xAxis);
svg.append('g')
.attr('transform', 'translate(' + padding + ', 0)')
.call(yAxis)
svg.selectAll('rect')
.data(arr)
.enter()
.append('rect')
.attr('fill', 'blue')
.attr('height', d => height - padding - yScale(d[1]))
.attr('width', d => bandScale.bandwidth())
.attr('x', (d, i) => (bandScale(years[i])))
.attr('y', d => yScale(d[1]))
.append('title')
.text((d, i) => years[i] + ': ' + d[1])
});
<script src="https://d3js.org/d3.v4.min.js"></script>

How can I make a bar chart starting from the 0 point of the y axis and not from the bottom of the svg?

I'm trying to make a bar chart but I can't figure out a way to make the bar start from the 0 point of y axis and not from the very bottom of the svg. How can I fix that?
let url = "https://raw.githubusercontent.com/freeCodeCamp/ProjectReferenceData/master/GDP-data.json";
const padding = 50;
const height = 460;
const width = 900;
var svg = d3.select('body')
.append('svg')
.attr('width', width)
.attr('height', height);
var arr = [];
d3.json(url, function(data) {
for (let i = 0; i < data.data.length; i++) arr[i] = data.data[i];
const yScale = d3.scaleLinear()
.domain([0, d3.max(arr, (d) => d[1])])
.range([height - padding, padding]);
const yAxis = d3.axisLeft(yScale);
svg.append('g')
.attr('transform', 'translate(' + padding + ', 0)')
.call(yAxis)
svg.selectAll('rect')
.data(arr)
.enter()
.append('rect')
.attr('fill', 'blue')
.attr('height', d => d[1] + padding)
.attr('width', 2.909090909090909)
.attr('x', (d, i) => padding + (3.2 * i))
.attr('y', d => yScale(d[1]))
.append('title')
.text(d => d[1])
});
<script src="https://d3js.org/d3.v4.min.js"></script>

You are incorrectly calculating the height of the rectangle, and not using your scale. It's also trickier since your use of padding is not the typical D3 convention.
svg.selectAll('rect')
.data(arr)
.enter()
.append('rect')
.attr('fill', 'blue')
.attr('height', d => height - padding - yScale(d[1]))

D3 line chart and adding data points real time

I am beginner to d3 and trying to create real time chart which adds in new values on the go. I want the chart to shift the old points to the left as new points are added. Below is my code but for some reason, the browser freezes with the code (I have commented out the .on() line in the end that causes the freeze).
What am I doing wrong?
<!DOCTYPE html>
<head></head>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js">
</script>
<script>
<!DOCTYPE html>
<head></head>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js">
</script>
<script>
var t = -1;
var n = 40;
var duration = 750;
var data = [];
console.log('hello');
function next() {
return {
time: ++t,
value: Math.random() * 10
}
}
var margin = {
top: 6,
right: 0,
bottom: 20,
left: 40
},
width = 560 - margin.right,
height = 120 - margin.top - margin.bottom;
var xScale = d3.scaleTime()
.domain([t - n + 1, t])
.range([0, width]);
var yScale = d3.scaleLinear()
.domain([0, 10])
.range([height, 0]);
var line = d3.line()
.x((d) => xScale(d.time))
.y((d) => yScale(d.value));
var svg = d3.select('body').append('p').append('svg');
var chartArea = svg.append('g')
.attr('transform', `translate(${margin.left}, ${margin.top})`);
chartArea.append('defs').append('clipPath')
.attr('id', 'clip2')
.append('rect')
.attr('x', 0)
.attr('y', 0)
.attr('width', width)
.attr('height', height);
chartArea.append('rect')
.attr('class', 'bg')
.attr('x', 0)
.attr('y', 0)
.attr('width', this.chartWidth)
.attr('height', this.chartHeight);
var xAxis = d3.axisBottom(xScale);
var xAxisG = chartArea.append('g')
.attr('class', 'x-axis')
.attr('transform', `translate(0, ${height})`);
xAxisG.call(xAxis);
d3.selectAll('x-axis path').style('stroke', 'red')
.style('stroke-width', 2);
var yAxis = d3.axisLeft(yScale);
var yAxisG = chartArea.append('g').attr('class', 'y-axis');
yAxisG.call(yAxis);
var grids = chartArea.append('g')
.attr('class', 'grid')
.call(d3.axisLeft(yScale).tickSize(-(width)).tickFormat((domain, number) => {
return ""
}));
var pathsG = chartArea.append('g')
.attr('id', 'paths')
.attr('class', 'paths')
.attr('clip-path', 'url(#clip2)');
tick();
function tick() {
console.log('working');
var newValue = {
time: ++t,
value: Math.random() * 10
};
data.push(newValue);
xScale.domain([newValue.time - n + 2, newValue.time]);
xAxisG.transition().duration(500).ease(d3.easeLinear).call(xAxis);
console.log('is it?');
var minerG = pathsG.selectAll('.minerLine').data([data]);
var minerGEnter = minerG.enter()
.append('g')
.attr('class', 'minerLine')
.merge(minerG);
var minerSVG = minerGEnter.selectAll('path').data((d) => [d]);
var minerSVGEnter = minerSVG.enter()
.append('path')
.attr('class', 'line')
.merge(minerSVG)
.transition()
.duration(500)
.ease(d3.easeLinear, 2)
.attr('d', line(data))
.on('end', () => {
requestAnimationFrame(tick)
})
}
</script>
</body>
</html>

The problem is caused by the fact that tick is called immediately and synchronously at the end of the transition. The CPU process executing the JavaScript remains busy updating data and chart, and is not available to do anything else on this tab.
One way to fix this is to use Window.requestAnimationFrame().
.on('end', () => {
requestAnimationFrame(tick)
})
The updated snippet below shows this solution in action.
It does not fix other issues not mentioned in the question, like the fact that no data is shown in the chart.
<!DOCTYPE html>
<head></head>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js">
</script>
<script>
var t = -1;
var n = 40;
var duration = 750;
var data = [];
console.log('hello');
function next() {
return {
time: ++t,
value: Math.random() * 10
}
}
var margin = {
top: 6,
right: 0,
bottom: 20,
left: 40
},
width = 560 - margin.right,
height = 120 - margin.top - margin.bottom;
var xScale = d3.scaleTime()
.domain([t - n + 1, t])
.range([0, width]);
var yScale = d3.scaleLinear()
.domain([0, 10])
.range([height, 0]);
var line = d3.line()
.x((d) => xScale(d.time))
.y((d) => yScale(d.value));
var svg = d3.select('body').append('p').append('svg');
var chartArea = svg.append('g')
.attr('transform', `translate(${margin.left}, ${margin.top})`);
chartArea.append('defs').append('clipPath')
.attr('id', 'clip2')
.append('rect')
.attr('x', 0)
.attr('y', 0)
.attr('width', width)
.attr('height', height);
chartArea.append('rect')
.attr('class', 'bg')
.attr('x', 0)
.attr('y', 0)
.attr('width', this.chartWidth)
.attr('height', this.chartHeight);
var xAxis = d3.axisBottom(xScale);
var xAxisG = chartArea.append('g')
.attr('class', 'x-axis')
.attr('transform', `translate(0, ${height})`);
xAxisG.call(xAxis);
d3.selectAll('x-axis path').style('stroke', 'red')
.style('stroke-width', 2);
var yAxis = d3.axisLeft(yScale);
var yAxisG = chartArea.append('g').attr('class', 'y-axis');
yAxisG.call(yAxis);
var grids = chartArea.append('g')
.attr('class', 'grid')
.call(d3.axisLeft(yScale).tickSize(-(width)).tickFormat((domain, number) => {
return ""
}));
var pathsG = chartArea.append('g')
.attr('id', 'paths')
.attr('class', 'paths')
.attr('clip-path', 'url(#clip2)');
tick();
function tick() {
console.log('working');
var newValue = {
time: ++t,
value: Math.random() * 10
};
data.push(newValue);
xScale.domain([newValue.time - n + 2]);
xAxisG.transition().duration(500).ease().call(xAxis);
console.log('is it?');
var minerG = pathsG.selectAll('.minerLine').data([data]);
var minerGEnter = minerG.enter()
.append('g')
.attr('class', 'minerLine')
.merge(minerG);
var minerSVG = minerGEnter.selectAll('path').data((d) => [d]);
var minerSVGEnter = minerSVG.enter()
.append('path')
.attr('class', 'line')
.merge(minerSVG)
.transition()
.duration(500)
.ease(d3.easeLinear, 2)
.attr('d', line(data))
.on('end', () => {
requestAnimationFrame(tick)
})
}
</script>
</body>
</html>

Plotting normal density function with d3 js

I'm trying to plot this continuous function with D3 js version 4 but i'm having many problems with arrays. this is my javascript code:
var x = d3.range(-4., 4.1, 0.1)
var fnorm = x => (1. / Math.sqrt(2 * Math.PI)) * Math.exp(-0.5 * Math.pow(x, 2))
var y = new Array()
for (var i = 0 ; i < x.length ; i++) {
y[i] = fnorm(x[i])
}
var dataset = []
for (var j = 0; j < x.length; j++) {
dataset[j] = []
dataset[j][0] = x[j]
dataset[j][1] = y[j]
}
console.log(dataset[0])
console.log(dataset[1])
var w = 500
var h = 500
var padding = 50
var xScale = d3.scaleLinear()
.domain([d3.min(x, function(d) { return d }), d3.max(x, function(d) { return d })])
.range([padding, w - padding * 2])
var yScale = d3.scaleLinear()
.domain([0, 0.4])
.range([h - padding, padding])
function mycanvas() {
var svg = d3.select('body')
.append('svg')
.attr('width', w)
.attr('height', h)
svg.append('rect')
.attr('width', '100%')
.attr('height', '100%')
.attr('fill', 'blue')
// Define the axis
var xAxis = d3.axisBottom().scale(xScale).ticks(9)
var yAxis = d3.axisLeft().scale(yScale).ticks(9)
// Create the axis
svg.append('g')
.attr('class', 'axis')
.attr('transform', 'translate(0,' + (h - padding) + ')')
.call(xAxis)
svg.append('g')
.attr('class', 'axis')
.attr('transform', 'translate(' + padding + ',0)')
.call(yAxis)
svg.selectAll('line')
.data(dataset)
.enter()
.append('line')
.attr('x1', function(d) {
return xScale(d[0])
})
.attr('y1', function(d) {
return yScale(d[1])
})
.attr('x2', function(d) {
return xScale(d[1])
})
.attr('y2', function(d) {
return yScale(d[0])
})
.attr('stroke', 'white')
}
function main() {
mycanvas()
}
window.onload = main
<script src="https://d3js.org/d3.v4.min.js"></script>
The main problem is when i try to plot with svg line i don't know how to fix the right way to call and apply dataset array with x1,y1,x2,y2

You could use d3.line to produce a path from dataset:
var line = d3.line()
.x(function(d) { return xScale(d[0]);})
.y(function(d) { return yScale(d[1]);});
svg.append("path")
.attr("d", line(dataset))
.attr("stroke", "white")
.attr("fill", "none");
Demo: https://jsfiddle.net/LukaszWiktor/kkxe5sbc/