Useful webdriver.io command to wait for things in the browser's JS execution environment

waitForBrowserSide.js

browser.addCommand('waitForBrowserSide', function waitForBrowserSide (callback) {
  return browser
    .timeoutsAsyncScript(10000)
    .executeAsync(function thisRunsInsideTheBrowser(callback, done) {
      setInterval(function () {
        if (callback()) {
          done();
        }
      }, 100);
    }, callback)
  ;
});