JSLint will throw the "Unexpected TODO comment" error when it encounters a comment in which the first word is "TODO". Here's an example:
This error is raised to highlight a lack of convention. Comments that start with the word "TODO" are commonly used to mark unfinished parts of code. JSLint takes the safe approach and assumes that your code is not production-ready if it contains such comments.
If you are happy with "TODO" comments being in your code, you can pass the todo option to JSLint to tell it to ignore them: