t.js

  var initializationPromise = utilsAsync.makePromise(function (resolve, reject) {

    checkPendo();

    function checkPendo () {
      var delay = 0;

      if (window.pendo === undefined) {
        if (delay < 8) {
          setTimeout(checkPendo, (delay = Math.max(delay *= 2, 1)) * 1000);
        } else {
          // TODO: handle failure(?)
          console.warn('pendo did not load');
          reject(new Error("pendo did not load"));
        }
      } else {
        resolve(window.pendo);
      }
    }
  });

// or 

var initializationPromise = utilsAsync.makePromise(function (resolve, reject) {
  var counter = 0;
  
  function checkPendo () {
    if (window.pendo === undefined) {
      if (counter < 8) {
        counter++;
        setTimeout(checkPendo, 1000);
      }
    } else {
      resolve(window.pendo);
    }
  }

  checkPendo();
});