Referring to a Component Instance
When a component is
render'ed', a React component instance is created from the passed configuration options. One can gain access to this instance and it's properties (e.g.,
this.props) and methods (e.g.,
this.setState()) in two ways.
The first way is by using the
this keyword from within a configuration function option. In the code example below all of the
console.log(this) statements will refer to the component instance.
The other way to gain a reference to a component instance involves making use of the return value from calling
ReactDOM.render(). In other words, the
ReactDOM.render() function will return a reference to the top most rendered component.
thiskeyword will commonly be used from within a component to access instance properties like
this.props.[NAME OF PROP],
this.state,. It will also be used to call class methods/properties, that all components share like