Passing a number to a component
You can either use:
<MyComponent param1={10} param2={20} />
Or:
<MyComponent {...{param1: 10, param2: 20}} />
It seems that in case of integers (and actually for strings as well) I should be passing the numbers via {}
like so:
React.render(<Rectangle intValue={10} stringValue={"Hello"} />, document.getElementById('container'));