assistant: Here's a basic example of creating a circle with each library, as well as some relevant differences and considerations for each library. To set up each library, you can either download the library files or use a CDN link. Make sure to include the library script tag in the HTML file before your own JavaScript file.

1. D3.js
   Primarily used for data-driven visualizations
   Operates on SVG elements
HTML:
```html
<!DOCTYPE html>
<html>
<head>
  <script src="https://d3js.org/d3.v7.min.js"></script>
</head>
<body>
  <svg width="100" height="100"></svg>
  <script src="your_script.js"></script>
</body>
</html>
```
your_script.js:
```javascript
const svg = d3.select("svg");
svg.append("circle")
   .attr("cx", 50)
   .attr("cy", 50)
   .attr("r", 25)
   .attr("fill", "blue");
```
2. Particles.js
   Used to create particle systems and backgrounds
HTML:
```html
<!DOCTYPE html>
<html>
<head>
  <script src="https://cdn.jsdelivr.net/particles.js/2.0.0/particles.min.js"></script>
</head>
<body>
  <div id="particles-js"></div>
  <script src="your_script.js"></script>
</body>
</html>
```
your_script.js:
```javascript
particlesJS('particles-js', {
  particles: {
    number: {
      value: 1
    },
    shape: {
      type: 'circle'
    },
    size: {
      value: 25
    }
  }
});
```
3. Matter.js
   Physics-based library, ideal for creating realistic animations
HTML:
```html
<!DOCTYPE html>
<html>
<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/matter-js/0.17.1/matter.min.js"></script>
</head>
<body>
  <canvas id="myCanvas" width="100" height="100"></canvas>
  <script src="your_script.js"></script>
</body>
</html>
```
your_script.js:
```javascript
const { Engine, Render, World, Bodies } = Matter;
const engine = Engine.create();
const canvas = document.getElementById('myCanvas');
const render = Render.create({
  canvas: canvas,
  engine: engine,
  options: {
    width: 100,
    height: 100,
    wireframes: false
  }
});

const circle = Bodies.circle(50, 50, 25, { render: { fillStyle: 'blue' } });
World.add(engine.world, [circle]);
Engine.run(engine);
Render.run(render);
```
4. Paper.js
   Vector graphics library, works on a scene graph concept
HTML
```html
<!DOCTYPE html>
<html>
<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/paper.js/0.12.15/paper-full.min.js"></script>
</head>
<body>
  <canvas id="myCanvas" resize></canvas>
  <script src="your_script.js"></script>
</body>
</html>
```
your_script.js:

```javascript
paper.setup('myCanvas');
const circle = new paper.Path.Circle(new paper.Point(50, 50), 25);
circle.fillColor = 'blue';
paper.view.draw();
```
5. Fabric.js
Object-based library, manipulates and interacts with canvas elements
HTML:
```html
<!DOCTYPE html>
<html>
<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/4.2.0/fabric.min.js"></script>

</head>
<body>
  <canvas id="myCanvas" width="100" height="100"></canvas>
  <script src="your_script.js"></script>
</body>
</html>
```
your_script.js:

```javascript
const canvas = new fabric.Canvas('myCanvas');
const circle = new fabric.Circle({
  left: 25,
  top: 25,
  radius: 25,
  fill: 'blue'
});
canvas.add(circle);
```
6. Chart.js
Primarily used for creating charts and graphs
Not suitable for creating individual shapes like circles

7. Two.js

2D drawing library that supports SVG, Canvas, and WebGL rendering

HTML:
```html
<!DOCTYPE html>
<html>
<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/two.js/0.7.7/two.min.js"></script>
</head>
<body>
  <div id="draw"></div>
  <script src="your_script.js"></script>
</body>
</html>
```
your_script.js:
```javascript
const elem = document.getElementById('draw');
const two = new Two({
  width: 100,
  height: 100
}).appendTo(elem);

const circle = two.makeCircle(50, 50, 25);
circle.fill = 'blue';
circle.noStroke();
two.update();
```
Differences and considerations:

1. D3.js is best suited for data-driven visualizations.
2. Particles.js is great for creating particle systems and backgrounds but isn't ideal for more complex graphics.
3. Matter.js focuses on physics-based animations and simulations.
4. Paper.js is a versatile vector graphics library with a scene graph concept.
5. Fabric.js is an object-based library that provides interactivity with canvas elements.
6. Chart.js is tailored for creating charts and graphs and is not suitable for creating individual shapes like circles.
7. Two.js supports various rendering types (SVG, Canvas, and WebGL) and is useful for creating 2D graphics.

Keep in mind the use case, complexity, and specific features of each library when deciding which one to use for your project.

Please let me know if there is anything else that I can assist you with.

prompter: Great, now tell me the most practical library for fast writing of websites on JS with libraries.

assistant: Sure, I can provide some information on creating a "Hello World" example with each of the libraries I mentioned earlier, as well as some tips on setup and relevant features.

D3.js:
To create a circle with D3.js, you can use the following code:

```js
d3.select("body")
  .append("svg")
  .append("circle")
  .attr("cx", 50)
  .attr("cy", 50)
  .attr("r", 25);
```

This code creates an SVG element and appends a circle to it with a center at (50,50) and a radius of 25 pixels. D3.js is a popular library for creating interactive data visualizations, and it provides a lot of powerful features for handling data, animations, and more.

Particles.js:
To create a circle with Particles.js, you can use the following code:

```js
particlesJS('my-canvas', {
  "particles": {
    "number": {
      "value": 1
    },
    "shape": {
      "type": "circle"
    },
    "size": {
      "value": 50
    }
  }
});
```

This code initializes Particles.js with a single particle of type "circle" and a size of 50 pixels. Particles.js is a library for creating particle effects and animations, and it can be used to create interesting visual effects.

Matter.js:
To create a circle with Matter.js, you can use the following code:

```js
var Engine = Matter.Engine,
    Render = Matter.Render,
    World = Matter.World,
    Bodies = Matter.Bodies;

var engine = Engine.create();

var render = Render.create({
    element: document.body,
    engine: engine
});

var circle = Bodies.circle(50, 50, 25);

World.add(engine.world, [circle]);

Engine.run(engine);
Render.run(render);
```

This code creates a Matter.js engine and renders a circle body with a center at (50,50) and a radius of 25 pixels. Matter.js is a library for creating physics simulations, and it provides powerful tools for creating complex physics-based interactions.

Paper.js:
To create a circle with Paper.js, you can use the following code:

```js
var canvas = document.getElementById('my-canvas');
paper.setup(canvas);

var circle = new paper.Path.Circle(new paper.Point(50,50), 25);
circle.fillColor = 'black';

paper.view.draw();
```

This code initializes a Paper.js canvas, creates a circle shape with a center at (50,50) and a radius of 25 pixels, and fills it with black. Paper.js is a library for creating vector graphics and animations, and it provides many tools for working with paths, colors, and transformations.

Fabric.js:
To create a circle with Fabric.js, you can use the following code:

```js
var canvas = new fabric.Canvas('my-canvas');

var circle = new fabric.Circle({
  left: 50,
  top: 50,
  radius: 25,
  fill: 'black'
});

canvas.add(circle);
```

This code initializes a Fabric.js canvas, creates a circle object with a center at (50,50) and a radius of 25 pixels, and fills it with black. Fabric.js is a library for creating interactive fabric objects, and it provides many features for working with colors, patterns, and animations.

Chart.js:
To create a circle with Chart.js, you can use the following code:

```js
var ctx = document.getElementById('my-canvas').getContext('2d');

var chart = new Chart(ctx, {
  type: 'pie',
  data: {
    labels: ['Circle'],
    datasets: [{
```