Building a bubble chart basically follows the same process as for a scatterplot, except that another scale is used to map a variable to bubble size. Thus, have a look to the scatterplot section for more examples.
The most basic bubble plot you can do in d3.js. Keeping only the core code.
A fourth categoric variable is mapped to the bubbles, giving a supplementary information.
Add a tooltip to each circle of the chart with a hover effect. Allows to give detail for each data point.
Here is the template I use to start a bubble chart project. Legend describes both size and color. Hover the legend to highlight the corresponging group. Hover a bubble to get country name.Get code
A selection of blocks involving bubble charts