Help to understand error - tooltip - Choropleth D3 data visualization project

I don’t understand what this error means:

  1. My tooltip should have a “data-education” property that corresponds to the “data-education” of the active area.
    AssertionError: Could not find property “data-education” in tooltip : expected null to not equal null

What is a ‘property’ in this context? How to add such a property to the tooltip?

Here is my code so far: https://codepen.io/zdflower/pen/vrwEEr

Please, help me! :confused::pray:

In this context (using D3), what’s being asked for can be achieved with the .attr method. You are already adding the relevant property in the function that’s drawing your counties map, for reference.

You are so right! I got it now.
Thanks!! :ok_woman: