React: checker is not a function

Question

I\'m getting this weird warning message in the console for my React app.

Warning: Failed propType: checker is not a function Check the render method of <

Answer 1

I was using oneOfType with array of strings as an argument when in fact I intended to use oneOf.

Something like that:

// Wrong!
PropTypes.oneOfType(['s', 'm'])

// Right!
PropTypes.oneOf(['s', 'm'])