better WeixinJSBridgeReady

whenWechatReady.js

window.whenWechatReady = (function () {
  var isReady = false;
  var tasks = [];
  var when = function (callback) {
    if (isReady) {
      return callback();
    }
    return tasks.push(callback);
  };
  document.addEventListener('WeixinJSBridgeReady', function () {
    isReady = true;
    while (tasks.length > 0) {
      tasks.shift()();
    }
  });
  return when;
})();