Given a React component props, generate potential react propTypes

genPropTypes.js

const topLevelBlacklist = [
  'children',
  'history',
  'location',
  'params',
  'route',
  'routeParams',
  'routes',
];

function genIndent(indent) {
  let s = '';
  for (let i = 0; i < indent; i++) {
    s += '  ';
  }
  return s;
}

function genProps(props, indent, blacklist = null) {
  let s = '';
  for (const p in props) {
    if (blacklist && blacklist.includes(p)) {
      continue;
    }

    const t = sniff(props[p], indent);
    if (!t) {
      continue;
    }

    s += genIndent(indent);
    s += `${p}: `;
    s += t;
    s += ',\n';
  }
  return s;
}

function sniff(prop, indent) {
  if (typeof prop === 'string') {
    return 'React.PropTypes.string';
  }

  if (typeof prop === 'number') {
    return 'React.PropTypes.number';
  }

  if (typeof prop === 'boolean') {
    return 'React.PropTypes.bool';
  }

  if (typeof prop === 'function') {
    return 'React.PropTypes.func';
  }

  if (typeof prop === 'symbol') {
    return 'React.PropTypes.symbol';
  }

  if (Array.isArray(prop)) {
    if (prop.length) {
      const t = sniff(prop[0], indent + 1);
      if (t) {
        return 'React.PropTypes.arrayOf(\n' +
               genIndent(indent + 1) + sniff(prop[0], indent + 1) +
               ',\n' + genIndent(indent) + ')';
      }
    }

    return 'React.PropTypes.array';
  }

  if (prop === null) {
    return false;
  }

  if (typeof prop === 'object') {
    if (Object.keys(prop).length) {
      let s = 'React.PropTypes.shape({\n';
      s += genProps(prop, indent + 1);
      s += genIndent(indent);
      s += '})';
      return s;
    }

    return 'React.PropTypes.object';
  }

  throw new Error(`unkown type: ${typeof prop}`);
}

module.exports = (props) => {
  let propTypes = 'static propTypes = {\n';
  propTypes += genProps(props, 1, topLevelBlacklist);
  propTypes += '}';

  return propTypes;
};