wait-for-global-variable.js

export function waitForGlobalVariable(objPath, interval, timeout, callback) {
  function find(objPath) {
    var found = window;
    objPath = objPath.split(".");
    while (objPath.length > 0) {
      var objPart = objPath.shift();
      if (objPart in found) {
        found = found[objPart];
      } else {
        return null;
      }
    }
    return found;
  }

  function findAndCallback(objPath, callback) {
    var found = find(objPath);
    if (found) {
      callback();
      return true;
    }
    return false;
  }

  var timer = 0;

  timer = setInterval(function () {
    var found = findAndCallback(objPath, callback);
    if (found) {
      clearInterval(timer);
    }
  }, interval);

  setTimeout(function () {
    clearInterval(timer);
  }, timeout);
}