Why is null needed in these examples?

Question

JavaScript

I started reading books on react. And in all examples, the author passes null as an argument. What for ?

var Component = React.createClass({
  render: function() {
    return React.DOM.span(null, "I'm so custom");
  }
});

React.render(
  React.createElement(Component),
  document.getElementById("app")
);

var Component = React.createClass({
  render: function() {
    return React.DOM.span(null, "My name is " + this.props.name);
  }
});
React.render(
  React.createElement(Component, {
    name: "Bob"
  }),
  document.getElementById("app")
);

Answer 1

This is the props of the component.