Extract/read React propTypes

Maybe adding a code example of what you are trying to do as I don't quite understand but why are you accessing propTypes? PropTypes don't contain values but rather expectations of what your value types should be for the different props passed into the component.

If you have a form that lets you alter the props I assume you are passing in the prop into the component that will be rendering the select component.You can access these props through props object.

If you are trying to validate the propTypes that can have the form of different types the following can be used:

optionalUnion: React.PropTypes.oneOfType([
  React.PropTypes.string,
  React.PropTypes.number,
  React.PropTypes.instanceOf(Message)
])

You can't read directly from propTypes since, as you said, they are defined as functions.

You could instead define your propTypes in an intermediary format, from which you'd generate your propTypes static.

var myPropTypes = {
  color: {
    type: 'oneOf',
    value: ['green', 'blue', 'yellow'],
  },
};

function processPropTypes(propTypes) {
  var output = {};
  for (var key in propTypes) {
    if (propTypes.hasOwnProperty(key)) {
      // Note that this does not support nested propTypes validation
      // (arrayOf, objectOf, oneOfType and shape)
      // You'd have to create special cases for those
      output[key] = React.PropTypes[propTypes[key].type](propTypes[key].value);
    }
  }
  return output;
}

var MyComponent = React.createClass({
  propTypes: processPropTypes(myPropTypes),

  static: {
    myPropTypes: myPropTypes,
  },
});

You could then access your custom propTypes format via MyComponent.myPropTypes or element.type.myPropTypes.

Here's a helper to make this process a little easier.

function applyPropTypes(myPropTypes, Component) {
  Component.propTypes = processPropTypes(myPropTypes);
  Component.myPropTypes = propTypes;
}

applyPropTypes(myPropTypes, MyComponent);