Working on a typeCheck function

typeCheck.js

function postTweet(tweet /*string*/, from /*string*/) {
  typeCheck(arguments);
}
postTweet('string', 'asdf');
postTweet('string', 222); //TypeError! run in console to see a nice error message!

function typeCheck(a) {
  var newArr = [].slice.call(a);
  var types = [];
  var f = a.callee.toString();
  f = f.substring(f.indexOf('(') + 1, f.indexOf(')') );
  f = f.split(',');
  f.forEach(function forEachArgStatement(s) {
    var start = s.indexOf('/*') + 2;
    types.push({
      name: s.substring(0, start - 2),
      type: s.substring(start, s.indexOf('*/', start) )
    });
  });
  //Might want to:
  /*
  try {
    args.callee = typeCheck.caller;
  } catch( _ ) { }
  */
  // From html5 boilerplate: https://github.com/h5bp/html5-boilerplate/commit/5370479476dceae7cc3ea105946536d6bc0ee468#js/plugins.js
  var callerName = a.callee.name;
  newArr.forEach(function forEachArg(arg, index){
    if (typeof arg !== types[index].type) {
      console.log('Bad arg:', arg);
      throw new TypeError(callerName + ' expects arg ' + (index+1) + ' `' + types[index].name.trim() + '` to be `' + types[index].type + '` but is `' + typeof arg + '` Bad arg above.');
    }
  });
}

Leave a comment!

WHAT ARE YOU, SOME KIND OF WIZARD?

perhaps. ^_^