WD.js JS condition asserter that retries on-error.

gistfile1.js

/* Version of wd.asserters.jsCondition that retries on-error.

   This is useful for cases where you need to assert a condition at a time when the page might
   be reloading -- in such a case, the assertion could reach the browser at a time when the document
   is not yet ready, triggering an error. This catches the error and retries.
   
   Usage:
   > browser.waitFor(jsConditionWithRetries('window.FOOBAR'), 5000, 500);
   
   (Requires Selenium Server >= 2.44.0)
*/
function jsConditionWithRetries(jsConditionExpr, retryCount, retryInterval) {
    
    retryCount = retryCount || 10;  // number of times to retry on command failure
	retryInterval = retryInterval || 500; // ms to wait before retries
	
	return new asserters.Asserter(function (browser, cb) {
		function runConditionWithRetries(retries) {
			browser.safeEval.apply(browser, [jsConditionExpr, function (err, res) {
				if (err) {
					if (retries) {
						console.warn('Encountered an issue making a JS assertion in the browser, retrying in ' + retryInterval + 'ms');
						setTimeout(function () {
							runConditionWithRetries(retries - 1);
						}, retryInterval);
					} else {
						return cb(err);
					}
				} else {
					cb(null, res, res);
				}
			}]);
		}
		runConditionWithRetries(retryCount);
	});
}