Express

In an Express app the browser script goes into the layout that renders the <head> of every page. The examples use EJS; the same two tags work in Pug, Handlebars or HTML you send with res.send.

Add the script#

Replace SITE_ID with the id from Settings → Sites in the ProductLense dashboard.

<meta charset="utf-8" />
<title><%= title %></title>
<script>window.productlense=window.productlense||function(){(window.productlense.q=window.productlense.q||[]).push(arguments)}</script>
<script defer data-site="SITE_ID" src="https://api.productlense.app/a.js"></script>

Include the partial in the <head> of your layout with <%- include('partials/head') %>. If you set a Content-Security-Policy with Helmet, allow https://api.productlense.app in script-src and connect-src; see Content Security Policy.

Identify users#

Pass the signed-in user's id to the template and print it as JSON, so quotes and < in the value cannot break out of the script:

app.use((req, res, next) => {
  // Escape "<" so the value can never close the script tag.
  res.locals.productLenseUserId = JSON.stringify(req.session?.userId ?? null).replace(/</g, '\\u003c');
  next();
});

<script>
  var uid = <%- productLenseUserId %>;
  if (uid) window.productlense('identify', String(uid));
</script>

Place this after the queue stub. Use the same id you store on the customer in your billing provider; see how payments are attributed.

Events from your server#

Actions that happen only on the server, such as a webhook that converts a trial, can be sent to the Events API with an API key. API keys are on the Scale plan; see server-side events.

Verify your installation#

1. Deploy, then open your site in a normal browser window.
2. Open the Live page in the ProductLense dashboard. Your visit appears within a few seconds.
3. In the browser's developer tools, the Network tab shows a POST to https://api.productlense.app/api/e with status 204.

An app running on localhost sends nothing unless you add data-dev="true" to the tag. Ad blockers in your own browser may block the request. If the visit does not appear, follow Verify your installation.