title: What is the difference between componentWillMount and componentDidMount in ReactJS?
body: <p>I looked at Facebook's documentation at (<a href="https://facebook.github.io/react/docs/component-specs.html" rel="noreferrer">React.Component</a>)  and it mentions how <code>componentWillMount</code> is invoked on the client/server whereas <code>componentDidMount</code> is invoked only on the client. What does <code>componentWillMount</code> do to the server?</p>