[Solved]-D3 tooltip error: "Cannot read property '-1' of undefined"-d3.js

What I've been able to find so far is if you do console.log(d) right before the problem area, you don't have a d.value defined. What I'm seeing instead is d.values, which is an array.

Also mousedate ends up as -1 because there isn't an index in dates that it's looking for.

I probably haven't found the whole solution, but fixing that should help get you back on track a bit, at least.