Use props validation everywhere

[slorber]

http://facebook.github.io/react/docs/reusable-components.html

React.createClass({
  propTypes: {
    // You can declare that a prop is a specific JS primitive. By default, these
    // are all optional.
    optionalArray: React.PropTypes.array,
    optionalBool: React.PropTypes.bool,
    optionalFunc: React.PropTypes.func,
    optionalNumber: React.PropTypes.number,
    optionalObject: React.PropTypes.object,
    optionalString: React.PropTypes.string,

    // You can ensure that your prop is limited to specific values by treating
    // it as an enum.
    optionalEnum: React.PropTypes.oneOf(['News','Photos']),

    // You can also declare that a prop is an instance of a class. This uses
    // JS's instanceof operator.
    someClass: React.PropTypes.instanceOf(SomeClass),

    // You can chain any of the above with isRequired to make sure an error is
    // thrown if the prop isn't provided.
    requiredFunc: React.PropTypes.func.isRequired

    // You can also specify a custom validator.
    customProp: function(props, propName, componentName) {
      if (!/matchme/.test(props[propName])) {
        throw new Error('Validation failed!')
      }
    }
  },
  /* ... */
});

Using props validation ensure that each component is used correctly, through a defined interface.
It's like assertions for a component done in a declarative way.

This should be used almost everywhere to help detect the consistency issues that could happen when the application grows.

We need to fail-fast to detect problems