Add event tracking documentation

- Add link to Event tracking in FE guides

doc/development/fe_guide/index.md

 # Frontend Development Guidelines
 
 > **Notice:**
-We are currently in the process of re-writing our development guide to make it easier to find information. The new guide is still WIP but viewable in [development/new_fe_guide](../new_fe_guide/index.md)
+> We are currently in the process of re-writing our development guide to make it easier to find information. The new guide is still WIP but viewable in [development/new_fe_guide](../new_fe_guide/index.md)
 
 This document describes various guidelines to ensure consistency and quality
 across GitLab's frontend team.
@@ -32,32 +32,41 @@ For our currently-supported browsers, see our [requirements][requirements].
 ---
 
 ## [Development Process](development_process.md)
+
 How we plan and execute the work on the frontend.
 
 ## [Architecture](architecture.md)
+
 How we go about making fundamental design decisions in GitLab's frontend team
 or make changes to our frontend development guidelines.
 
 ## [Testing](../testing_guide/frontend_testing.md)
+
 How we write frontend tests, run the GitLab test suite, and debug test related
 issues.
 
 ## [Design Patterns](design_patterns.md)
+
 Common JavaScript design patterns in GitLab's codebase.
 
 ## [Vue.js Best Practices](vue.md)
+
 Vue specific design patterns and practices.
 
 ## [Vuex](vuex.md)
+
 Vuex specific design patterns and practices.
 
 ## [Axios](axios.md)
+
 Axios specific practices and gotchas.
 
 ## [GraphQL](graphql.md)
+
 How to use GraphQL
 
 ## [Icons and Illustrations](icons.md)
+
 How we use SVG for our Icons and Illustrations.
 
 ## [Components](components.md)
@@ -81,23 +90,26 @@ Our SCSS conventions which are enforced through [scss-lint][scss-lint].
 ---
 
 ## [Performance](performance.md)
+
 Best practices for monitoring and maximizing frontend performance.
 
 ---
 
 ## [Security](security.md)
+
 Frontend security practices.
 
 ---
 
 ## [Accessibility](accessibility.md)
+
 Our accessibility standards and resources.
 
 ## [Internationalization (i18n) and Translations](../i18n/externalization.md)
+
 Frontend internationalization support is described in [this document](../i18n/).
 The [externalization part of the guide](../i18n/externalization.md) explains the helpers/methods available.
 
-
 [rails]: http://rubyonrails.org/
 [haml]: http://haml.info/
 [hamlit]: https://github.com/k0kubun/hamlit
@@ -116,6 +128,7 @@ The [externalization part of the guide](../i18n/externalization.md) explains the
 ---
 
 ## [DropLab](droplab/droplab.md)
+
 Our internal `DropLab` dropdown library.
 
 - [DropLab](droplab/droplab.md)

doc/development/new_fe_guide/event_tracking.md

+# Event Tracking
+
+We use [Snowplow](https://github.com/snowplow/snowplow) for tracking custom events.
+
+## Generic tracking function
+
+In addition to Snowplow's built-in method for tracking page views, we use a generic tracking function which enables us to selectively apply listeners to events.
+
+The generic tracking function can be imported in EE-specific JS files as follows:
+
+```javascript
+import { trackEvent } from `ee/stats`;
+```
+
+This gives the user access to the `trackEvent` method, which takes the following parameters:
+
+| parameter        | type   | description                                                                                                                                                                                                                                                                                                                            | required |
+| ---------------- | ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- |
+| `category`       | string | Describes the page that you're capturing click events on. Unless infeasible, please use the Rails page attribute `document.body.dataset.page` by default.                                                                                                                                                                              | true     |
+| `eventName`      | string | Describes the action the user is taking. The first word should always describe the action. For example, clicks should be `click` and activations should be `activate`. Use underscores to describe what was acted on. For example, activating a form field would be `activate_form_input`. Clicking on a dropdown is `click_dropdown`. | true     |
+| `additionalData` | object | Additional data such as `label`, `property`, and `value` as described [in our Feature Instrumentation taxonomy](https://about.gitlab.com/handbook/product/feature-instrumentation/#taxonomy).                                                                                                                                          | false    |
+
+Read more about instrumentation and the taxonomy in the [Product Handbook](https://about.gitlab.com/handbook/product/feature-instrumentation).
+
+### Tracking in `.js` and `.vue` files
+
+The most simple use case is to add tracking programmatically to an event of interest in Javascript.
+
+The following example demonstrates how to track a click on a button in Javascript by calling the `trackEvent` method explicitly:
+
+```javascript
+import { trackEvent } from `ee/stats`;
+
+trackEvent('dashboard:projects:index', 'click_button', {
+    label: 'create_from_template',
+    property: 'template_preview',
+    value: 'rails',
+});
+```
+
+### Tracking in HAML templates
+
+Sometimes we want to track clicks for multiple elements on a page. Creating event handlers for all elements could soon turn into a tedious task.
+
+There's a more convenient solution to this problem. When working with HAML templates, we can add `data-track-*` attributes to elements of interest. This way, all elements that have both `data-track-label` and `data-track-event` attributes assigned get marked for event tracking. All we have to do is call the `bindTrackableContainer` method on a container which allows for better scoping.
+
+Below is an example of `data-track-*` attributes assigned to a button in HAML:
+
+```ruby
+%button.btn{ data: { track_label: "create_from_template", track_property: "template_preview", track_event: "click_button", track_value: "my-template" } }
+```
+
+By calling `bindTrackableContainer('.my-container')`, click handlers get bound to all elements located in `.my-container` provided that they have the necessary `data-track-*` attributes assigned to them.
+
+```javascript
+import Stats from 'ee/stats';
+
+document.addEventListener('DOMContentLoaded', () => {
+  Stats.bindTrackableContainer('.my-container', 'category');
+});
+```
+
+The second parameter in `bindTrackableContainer` is optional. If omitted, the value of `document.body.dataset.page` will be used as category instead.
+
+Below is a list of supported `data-track-*` attributes:
+
+| attribute             | description                                                                                                                                                                                                     | required |
+| --------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------- |
+| `data-track-label`    | The `label` in `trackEvent`                                                                                                                                                                                     | true     |
+| `data-track-event`    | The `eventName` in `trackEvent`                                                                                                                                                                                 | true     |
+| `data-track-property` | The `property` in `trackEvent`. If omitted, an empty string will be used as a default value.                                                                                                                    | false    |
+| `data-track-value`    | The `value` in `trackEvent`. If omitted, this will be `target.value` or empty string. For checkboxes, the default value being tracked will be the element's checked attribute if `data-track-value` is omitted. | false    |
+
+Since Snowplow is an Enterprise Edition feature, it's necessary to create a CE backport when adding `data-track-*` attributes to HAML templates in most cases.

doc/development/new_fe_guide/index.md

@@ -27,6 +27,10 @@ Learn about all the internal JavaScript modules that make up our frontend.
 
 Style guides to keep our code consistent.
 
+## [Event Tracking with Snowplow](event_tracking.md)
+
+How we use Snowplow to track custom events.
+
 ## [Tips](tips.md)
 
 Tips from our frontend team to develop more efficiently and effectively.