wait window[obj]

wait.js

var wait = function (name, context) {
  context = context || window;
  var isReady = false;
  var tasks = [];
  var when = function (callback) {
    if (isReady) {
      return callback();
    }
    return tasks.push(callback);
  };
  var check = function (next) {
    var again = function () {
      console.log('check');
      setTimeout(function () {
        if (typeof context[name] === 'undefined') {
          again();
        } else {
          next();
        }
      }, 200);
    };
    again();
  };
  check(function () {
    isReady = true;
    while (tasks.length > 0) {
      tasks.shift()();
    }
  });
  return when;
};