React TypeError this._test is not a function

Question

Since im new to JavaScript and React, i really have problems figuring out the right syntax.

Here my problem:

_handleDrop(files) should call the

Answer 1

Also, this error can also occur (not in the context of question aske), when Some One passes a function down to a Child Component with wrong name, i.e., the function accessed in the Child Component is not defined due to spelling mistake.

I came here to figure that, but found out that was the case with me. :) Hope it will help someone.