This example demonstrates how D3’s data join can drive canvas rendering through a custom HTML element as an intermediate container. The visualization displays a grid of colored cells, with the number of cells controlled by a text input, and animates their appearance. The code binds data to custom elements using D3’s `selectAll`, `enter`, and `merge`, then draws each cell’s position and fill style onto a 2D canvas context, using a `d3.scaleSequential` color scale and `d3.timer` for animation.