Here are ten advanced features, tips, and tricks of the D3.js library that few people may know about:

1. Custom Interpolation: D3.js allows you to define custom interpolation functions to create smooth transitions between values. You can use the d3.interpolate() function to create your own interpolation logic based on specific requirements.

2. Geo Projections: D3.js provides a wide range of geographical projections that can be used to visualize spatial data on maps. You can choose from various projections like Mercator, Albers, Orthographic, and more, depending on your visualization needs.

3. Force-Directed Graphs: D3.js includes a powerful force-directed graph layout algorithm that can be used to create interactive and dynamic network visualizations. The d3.forceSimulation() function allows you to simulate physical forces and create visually appealing graphs.

4. Custom Shapes: While D3.js provides built-in shapes like circles, rectangles, and lines, you can also create custom shapes using SVG path elements. By defining your own path data, you can draw complex shapes and icons in your visualizations.

5. Brush and Zoom: D3.js offers brush and zoom functionality that allows users to interactively select and explore specific regions of a visualization. The d3.brush() and d3.zoom() functions enable you to add these interactive features to your charts and maps.

6. Chord Diagrams: D3.js can be used to create chord diagrams, which are useful for visualizing relationships between entities. The d3.chord() function helps in generating the necessary data structure and rendering the chord diagram.

7. Voronoi Diagrams: D3.js provides support for creating Voronoi diagrams, which partition a plane into regions based on a set of points. Voronoi diagrams can be used for various purposes, such as nearest-neighbor analysis or creating interactive hover effects.

8. Custom Easing Functions: D3.js allows you to define custom easing functions to control the timing and behavior of transitions. You can create your own easing functions using mathematical formulas or by combining existing easing functions provided by D3.js.

9. Hierarchical Edge Bundling: D3.js offers techniques for visualizing hierarchical data using edge bundling. This technique helps in reducing visual clutter by bundling similar edges together, making it easier to understand the relationships between nodes in a hierarchical structure.

10. Reusable Chart Components: D3.js promotes the concept of reusable chart components. By encapsulating the logic and rendering of chart elements into reusable functions or classes, you can create modular and maintainable code. This allows you to easily compose and customize charts based on your specific requirements.

These are just a few examples of the advanced features and techniques available in D3.js. The library is incredibly versatile and offers a wide range of possibilities for data visualization and interaction. Exploring the D3.js documentation, examples, and community resources can help you uncover even more hidden gems and tricks to enhance your visualizations.