Three.js — library written in JavaScript and used to create and display 3D graphics in web applications.

Official website: https://threejs.org

Possibilities:
• Elements: Canvas, SVG or WebGL
• Scene: add and delete objects in real time; fog
• Cameras: Perspective or orthographic
• Animation: wireframes, quick kinematics, reverse kinematics, frame-by-frame animation
• Light sources: external, directional, point; shadows: thrown and received
• Shaders: full access to all OpenGL shader (GLSL)
• Objects: nets, particles, sprites, lines, skeletal animation and more
• Geometry: plane, cube, sphere, torus, 3D text and more; modifiers: fabric, extrusion
• Data loaders: binary, images, JSON, and scene
• Export and Import: Utilities that create Three.js-compatible JSON files from formats: Blender, openCTM, FBX, 3D Studio Max, and Wavefront .obj file
• Support: The library API documentation is in the process of being constantly expanded and supplemented, there is a public forum and an extensive community

Library Three.js works in all browsers.
If your browser supports the technology WebGL then uses WebGL
If your browser doesn't support the technology WebGL , then works with HTML element Canvas and uses his calculations 3D.

Step 1. (create on disk D: Folder My)
Let's stand inside the folder D:/My

Step 2. (download the source code Tree.js)
To download the source code Tree.js in the command line run
git clone https://github.com/mrdoob/three.js.git

On the screen we will see (500 mb Loads)

When finished, we will open Windows Explorer and see the source files Node.js

Step 1. (Set Node.js)
Read How to Install Node.js ...

Step 2. (let's stand inside the folder D:/My/three.js)

Step 3. (at the command prompt run the command npm install)

 
Step 4. (at the command prompt run the command npm run build)

The result will be the collected file:
D:/My/build/three.js