JSX is not HTML JSX is not understood by browsers. If you try to execute the buttonv function in a regular browser console. function Button (props) {
return React.createElement(
"button",
{ type: "submit" },
props.label
);
}ReactDOM.render(
React.createElement(Button, { label: "Save"}),
mountNode
); components using classes React supports creating components through the JavaScript class syntax as well.