Quickstart: Analytics.js

This tutorial will help you start sending data from your website to Segment and any of our destinations, using our Analytics.js library. As soon as you’re setup you’ll be able to turn on any new destinations with the flip of a switch!

If you want to dive deeper at any point, check out the Analytics.js reference.

Step 1: Copy the Snippet

Installing Segment is easy, just paste this snippet into the head of your site:

<script type="text/javascript">
  !function(){var analytics=window.analytics=window.analytics||[];if(!analytics.initialize)if(analytics.invoked)window.console&&console.error&&console.error("Segment snippet included twice.");else{analytics.invoked=!0;analytics.methods=["trackSubmit","trackClick","trackLink","trackForm","pageview","identify","reset","group","track","ready","alias","debug","page","once","off","on"];analytics.factory=function(t){return function(){var e=Array.prototype.slice.call(arguments);e.unshift(t);analytics.push(e);return analytics}};for(var t=0;t<analytics.methods.length;t++){var e=analytics.methods[t];analytics[e]=analytics.factory(e)}analytics.load=function(t,e){var n=document.createElement("script");n.type="text/javascript";n.async=!0;n.src="https://cdn.segment.com/analytics.js/v1/"+t+"/analytics.min.js";var a=document.getElementsByTagName("script")[0];a.parentNode.insertBefore(n,a);analytics._loadOptions=e};analytics.SNIPPET_VERSION="4.1.0";
<script type="text/javascript">

    // Create a queue, but don't obliterate an existing one!
    var analytics = window.analytics = window.analytics || [];

    // If the real analytics.js is already on the page return.
    if (analytics.initialize) return;

    // If the snippet was invoked already show an error.
    if (analytics.invoked) {
      if (window.console && console.error) {
        console.error('Segment snippet included twice.');

    // Invoked flag, to make sure the snippet
    // is never invoked twice.
    analytics.invoked = true;

    // A list of the methods in Analytics.js to stub.
    analytics.methods = [

    // Define a factory to create stubs. These are placeholders
    // for methods in Analytics.js so that you never have to wait
    // for it to load to actually record data. The `method` is
    // stored as the first argument, so we can replay the data.
    analytics.factory = function(method){
      return function(){
        var args = Array.prototype.slice.call(arguments);
        return analytics;

    // For each of our methods, generate a queueing stub.
    for (var i = 0; i < analytics.methods.length; i++) {
      var key = analytics.methods[i];
      analytics[key] = analytics.factory(key);

    // Define a method to load Analytics.js from our CDN,
    // and that will be sure to only ever load it once.
    analytics.load = function(key, options){
      // Create an async script element based on your key.
      var script = document.createElement('script');
      script.type = 'text/javascript';
      script.async = true;
      script.src = 'https://cdn.segment.com/analytics.js/v1/'
        + key + '/analytics.min.js';

      // Insert our script next to the first script element.
      var first = document.getElementsByTagName('script')[0];
      first.parentNode.insertBefore(script, first);
      analytics._loadOptions = options;

    // Add a version to keep track of what's in the wild.
    analytics.SNIPPET_VERSION = '4.1.0';

    // Load Analytics.js with your key, which will automatically
    // load the tools you've enabled for your account. Boosh!

    // Make the first page call to load the integrations. If
    // you'd like to manually name or tag the page, edit or
    // move this call however you'd like.


When you paste it, you’ll need to replace YOUR_WRITE_KEY with your Segment project’s Write Key, which you can find in your project setup guide or settings.

That snippet will load Analytics.js onto the page asynchronously, so it won’t affect your page load speed. As soon as that snippet is running on your site, you can start turning on any destinations on your Segment destinations page and they will start loading on your site automatically!

Note that you’ll want to remove other native 3rd party destination code that you have on your site since it may cause issues if you turn on those same destinations (e.g. Google Analytics, Mixpanel, Customer.io, etc.) via Segment.

Fun fact: if you only want the most basic Google Analytics setup you can stop reading right now. You’re done! Just switch on Google Analytics in our interface.

However, lots of analytics and marketing tools will need to record who each user is on your site. If you’re looking to use any tool that deals with the identity of your users, read on about the identify method…

Step 2: Identify Users

The identify method is how you tell Segment who the current user is. It includes a unique User ID and any optional traits you know about them. You can read more about it in the identify reference.

Note: You won’t need to call identify for anonymous visitors to your site. We’ll automatically assign them an anonymousId, so just calling page and track will still work just fine without identify.

Here’s what a basic call to identify might look like:

analytics.identify('f4ca124298', {
  name: 'Michael Bolton',
  email: 'mbolton@example.com'

That’s identifying Michael by his unique User ID (the one you know him by in your database) and labeling him with name and email traits.

Hold up though! When you actually put that code on your site, you’ll need to replace all those hard-coded strings with details about the currently logged-in user.

To do that, we recommend using a backend template to inject an identify call straight into the footer of every page of your site where the user is logged in. That way, no matter what page the user first lands on, they will always be identified. You don’t need to call identify if your unique identifier (userId) is not known.

Depending on your templating language, that would look something like this:

analytics.identify(' {{user.id}} ', {
  name: '{{user.fullname}}',
  email: '{{user.email}}'

With that call on your page, you’re now successfully identifying every user that visits your site.

Second fun fact: if you only want to use a basic CRM setup, you can call it a day right now. Just switch on Salesforce, Intercom, or any other CRM you’d like to use from our interface and we’ll start sending all of your user data to it!

Of course, lots of analytics tools record more than just identities… they record the actions each user performs too! If you’re looking for a complete event tracking analytics setup, keep reading…

Step 3: Track Actions

The track method is how you tell Segment about which actions your users are performing on your site. Every action triggers what we call an “event”, which can also have associated properties. You can read more about track in the track reference.

Here’s what a call to track might look like when a user signs up:

analytics.track('Signed Up', {
  plan: 'Enterprise'

That’s just telling us that your user just triggered the Signed Up event and chose your hypothetical 'Enterprise' plan. Properties can be anything you want to record, for example:

analytics.track('Article Bookmarked', {
  title: 'Snow Fall',
  subtitle: 'The Avalanche at Tunnel Creek',
  author: 'John Branch'

You’ll want to track events that are indicators of success for your site, like Signed Up, Item Purchased or Article Bookmarked.

To get started, we recommend tracking just a few important events. You can always add more later!

Once you’ve added a few track calls, you’re done! You successfully installed Analytics.js tracking. Now you’re ready to turn on any destination you fancy from our interface, margarita in hand.

What’s Next?

We just walked through the quickest way to get started with Segment using Analytics.js. You might also want to check out our full Analytics.js reference to see what else is possible, or read about the Tracking API methods to get a sense for the bigger picture.

If you’re running an Ecommerce site or app you should also check out our Ecommerce API reference to make sure your products and checkout experience are instrumented properly!

This page was last modified: 09 Mar 2020

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