revision: 26a949df85a1f9577e8080e19f2196c8a3db17ec

json (2.6.0)

racc (1.6.0)

tzinfo-data (1.2021.4)

"tippy.js": "5.2.0",

Basic cache storage is available through the `cache` object, which has the following methods defined:

- Obtains a cached value for the provided `key`, invoking the callback if the value is missing or has expired. The `ttl` is the maximum duration in milliseconds the value can be cached. If omitted or set to `-1`, the value will have no expiry.

- Immediately remove the value associated with the `key`.

Some important notes about the cache:

- When testing functions in the code editor, the cache will be empty because each test temporarily deploys a new instance of the function.

- Values in the cache are not shared between concurrently-running function instances; they are process-local which means that high-volume functions will have many separate caches.

- Values may be expunged at any time, even before the configured TTL is reached. This can happen due to memory pressure or normal scaling activity. Minimizing the size of cached values can improve your hit/miss ratio.

- Functions that receive a low volume of traffic may be temporarily suspended, during which their caches will be emptied. In general, caches are best used for high-volume functions and with long TTLs.

const val = await cache.load("mycachekey", ttl, async () => {

analytics.debug(true);

When you develop against Analytics 2.0, the plugins you write can augment functionality, enrich data, and control the flow and delivery of events. From modifying event payloads to changing analytics functionality, plugins help to speed up the process of getting things done.

Though middlewares function the same as plugins, it's best to use plugins as they are easier to implement and are more testable.

Plugins are bound by Analytics 2.0 which handles operations such as observability, retries, and error handling. There are two different categories of plugins:

* **Critical Plugins**: Analytics.js expects this plugin to be loaded before starting event delivery. Failure to load a critical plugin halts event delivery. Use this category sparingly, and only for plugins that are critical to your tracking.

* **Non-critical Plugins**: Analytics.js can start event delivery before this plugin finishes loading. This means your plugin can fail to load independently from all other plugins. For example, every Analytics.js destination is a non-critical plugin. This makes it possible for Analytics.js to continue working if a partner destination fails to load, or if users have ad blockers turned on that are targeting specific destinations.

Non-critical plugins run through a timeline that executes in order of insertion based on the entry type. Segment has these five entry types of non-critical plugins:

Type | Details

---- | -------

`before` | Executes before event processing begins. These are plugins that run before any other plugins run. <br><br>For example, validating events before passing them along to other plugins. A failure here could halt the event pipeline. <br><br> See the example of how Analytics.js uses the [Event Validation plugin](https://github.com/segmentio/analytics-next/blob/master/src/plugins/validation/index.ts){:target="_blank"} to verify that every event has the correct shape.

`enrichment` | Executes as the first level of event processing. These plugins modify an event. <br><br> See the example of how Analytics.js uses the [Page Enrichment plugin](https://github.com/segmentio/analytics-next/blob/master/src/plugins/page-enrichment/index.ts){:target="_blank"} to enrich every event with page information.

`destination` | Executes as events begin to pass off to destinations. <br><br> This doesn’t modify the event outside of the specific destination, and failure doesn’t halt the execution.

`after` | Executes after all event processing completes. You can use this to perform cleanup operations. <br><br>An example of this is the [Segment.io Plugin](https://github.com/segmentio/analytics-next/blob/master/src/plugins/segmentio/index.ts){:target="_blank"} which waits for destinations to succeed or fail so it can send it observability metrics.

`utility` | Executes once during the bootstrap, to give you an outlet to make any modifications as to how Analytics.js works internally. This allows you to augment Analytics.js functionality.

Here's an example of a plugin that converts all track event names to lowercase before the event goes through the rest of the pipeline:

export const lowercase: Plugin = {

name: 'Lowercase events',

type: 'enrichment',

version: '1.0.0',

isLoaded: () => true,

load: () => Promise.resolve(),

track: (ctx) => {

ctx.updateEvent('event', ctx.event.event.toLowerCase())

return ctx

}

}

const identityStitching = () => {

let user

const identity = {

// Identifies your plugin in the Plugins stack.

// Access `window.analytics.queue.plugins` to see the full list of plugins

name: 'Identity Stitching',

// Defines where in the event timeline a plugin should run

type: 'enrichment',

version: '0.1.0',

// use the `load` hook to bootstrap your plugin

// The load hook will receive a context object as its first argument

// followed by a reference to the analytics.js instance from the page

load: async (_ctx, ajs) => {

user = ajs.user()

},

// Used to signal that a plugin has been property loaded

isLoaded: () => user !== undefined,

// Applies the plugin code to every `identify` call in Analytics.js

// You can override any of the existing types in the Segment Spec.

async identify(ctx) {

// Request some extra info to enrich your `identify` events from

// an external API.

const req = await fetch(

`https://jsonplaceholder.typicode.com/users/${ctx.event.userId}`

)

const userReq = await req.json()

// ctx.updateEvent can be used to update deeply nested properties

// in your events. It's a safe way to change events as it'll

// create any missing objects and properties you may require.

ctx.updateEvent('traits.custom', userReq)

user.traits(userReq)

// Every plugin must return a `ctx` object, so that the event

// timeline can continue processing.

return ctx

},

}

return identity

}

await window.analytics.register(identityStitching())

Here's an example of a `utility` plugin that allows you to change the format of the anonymous_id cookie:

window.analytics.ready(() => {

window.analytics.register({

name: 'Cookie Compatibility',

version: '0.1.0',

type: 'utility',

load: (_ctx, ajs) => {

const user = ajs.user()

const cookieJar = user.cookies

const cookieSetter = cookieJar.set.bind(cookieJar)

// blindly convert any values into JSON strings

cookieJar.set = (key, value, opts) => cookieSetter(key, JSON.stringify(value), opts)

// stringify any existing IDs

user.anonymousId(user.anonymousId())

user.id(user.id())

},

isLoaded: () => true

})

})

You can view Segment's [existing plugins](https://github.com/segmentio/analytics-next/tree/master/src/plugins){:target="_blank"} to see more examples.

Registering plugins enable you to modify your analytics implementation to best fit your needs. You can register a plugin using this:

await window.analytics.register(pluginA, pluginB, pluginN)

| Team | July 6, 2021 |

Once a source moves to Analytics.js 2.0, you can follow the steps above in [Manual migration](#manual-migration) back to roll back to Analytics.js Classic.

If the source you intend to upgrade uses the in-domain instrumentation as well as a custom "Alias for analytics.js", then you should update the AJS snippet to the latest version (4.15.3 or higher) before you toggle on Analytics.js 2.0.

Analytics.js 2.0 asynchronously loads different pieces of the library as needed. If the source you're upgrading uses a strict Content Security Policy (CSP) that allows JavaScript to be downloaded from specific locations, then you need to update the CSP to account for all the pieces used for Analytics.js 2.0. Therefore, beyond allowing the main analytics.min.js script, you should allow the following paths in your CSP:

- `https://cdn.segment.com/analytics-next/bundles/*`

popper.js@^1.16.0:

version "1.16.1"

resolved "https://registry.yarnpkg.com/popper.js/-/popper.js-1.16.1.tgz#2a223cb3dc7b6213d740e40372be40de43e65b1b"

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tippy.js@5.2.0:

version "5.2.0"

resolved "https://registry.yarnpkg.com/tippy.js/-/tippy.js-5.2.0.tgz#5e5a13a196ad2e39c7ee6cac5bfdb0513e797501"

integrity sha512-bmZu+TP1Fs6+1cq0GI1lfS9R0QxXDthP45zNGSLLMY5p2uC8sODNL4TiUOhEG25q5upk5LUrTnCkc+Q3H2aZJQ==

popper.js "^1.16.0"