ReactJS component names must begin with capital letters?

Question

I am playing around with the ReactJS framework on JSBin.

I have noticed that if my component name starts with a lowercase letter it does not work.

For instan

Answer 1

From the official React reference:

When an element type starts with a lowercase letter, it refers to a built-in component like or and results in a string 'div' or 'span' passed to React.createElement. Types that start with a capital letter like compile to React.createElement(Foo) and correspond to a component defined or imported in your JavaScript file.

Also note that:

We recommend naming components with a capital letter. If you do have a component that starts with a lowercase letter, assign it to a capitalized variable before using it in JSX.

Which means one has to use:

const Foo = foo; before using foo as a Component element in JSX.