Error on loading analytics.js asynchronously after page load

[robbles]

I'm seeing an error when trying to load analytics.js later on, after the page has loaded. I have a function, loadAnalyticsJs which is called later on in the page execution, since we only want to track a small subset of page views.

// Function to lazy-load analytics.js
var loadAnalyticsJs = function() {
  var analytics=analytics||[];analytics.load=function(e){var t=document.createElement("script");t.type="text/javascript",t.async=!0,t.src=("https:"===document.location.protocol?"https://":"http://")+"d2dq2ahtl5zl1z.cloudfront.net"+"/analytics.js/v1/"+e+"/analytics.min.js";var n=document.getElementsByTagName("script")[0];n.parentNode.insertBefore(t,n);var r=function(e){return function(){analytics.push([e].concat(Array.prototype.slice.call(arguments,0)));};},s=["identify","track"];for(var i=0;i<s.length;i++)analytics[s[i]]=r(s[i]);},
  analytics.load("XXXXXXX");
};

// Example of usage that causes error
setTimeout(loadAnalyticsJs, 10000);

When this is used, I see this error in the console:

Uncaught TypeError: Cannot read property 'length' of undefined analytics.min.js:4

I haven't had the chance to look through the un-minified source for analytics.js yet, but I'm guessing this has something to do with inspecting the script tags on the page, and that analytics.js is assuming the presence of a script tag that loaded it?

[robbles]

Problem solved - the line that throws the exception was looking for window.analytics, which of course is not defined by that snippet, because it assumes it's running in the global scope.

I changed it to the following code and now analytics.js loads without errors. However, I think that the loading snippet should be changed to accommodate loading from a function, since it's a small fix.

var loadAnalyticsJs = function() {
  var analytics=analytics||[];analytics.load=function(e){var t=document.createElement("script");t.type="text/javascript",t.async=!0,t.src=("https:"===document.location.protocol?"https://":"http://")+"d2dq2ahtl5zl1z.cloudfront.net"+"/analytics.js/v1/"+e+"/analytics.min.js";var n=document.getElementsByTagName("script")[0];n.parentNode.insertBefore(t,n);var r=function(e){return function(){analytics.push([e].concat(Array.prototype.slice.call(arguments,0)));};},s=["identify","track"];for(var i=0;i<s.length;i++)analytics[s[i]]=r(s[i]);},
  window.analytics = analytics;
  analytics.load("XXXXXXX");
};

[ianstormtaylor]

Hey @robbles I'm gonna close this for now, but keep attaching to window in mind in case it comes up again.