Javascript Tracker Core

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The Snowplow JavaScript Tracker Core is an node module, available on npm, providing functionality common to both the server-side Snowplow Node.js Tracker and the client-side Snowplow JavaScript Tracker. It supports all the Snowplow event types. Custom contexts and timestamps can be added to all events.

It is automatically included when using the Node.js or JavaScript trackers.

It has two main types of method: setter methods and tracking methods. Setter methods like setUserId store a name-value pair to be added to all future events, while tracking methods like trackPageView track a specific event.

1. Setup

Compatibility

Current release: 4.6.8

The current release of Snowplow Tracker Core is compatible with Node.js versions 10, 12 and 14. Installing it requires npm or yarn.

Installation

Setting up the tracker should be straightforward if you are familiar with npm:

bash
npm install snowplow-tracker-core

bash
yarn add snowplow-tracker-core

2. Initialization

Requiring the module

Require the Snowplow Tracker Core module into your code like so:

javascript
var trackerCore = require('snowplow-tracker-core');

or if using ES Modules, import like so:

javascript
import { trackerCore } from 'snowplow-tracker-core';

Creating a tracker core instance

The tracker core constructor takes two parameters:

A boolean value indicating whether unstructured events and custom contexts should be base 64 encoded (which defaults to true)
An optional callback to be executed on every payload before it is returned

javascript
const t = trackerCore(false, console.log);

The above example would create a tracker core instance which doesn't use base 64 encoding and which logs all payloads it creates to the console.

3. Setter methods

The core instance maintains a dictionary called payloadPairs containing persistent name-value pairs which are added to every payload. You can interact with these through the following methods:

`addPayloadPair()`

Adds a single name-value pair to payloadPairs.

javascript
t.addPayloadPair('myKey', 'myValue');

`addPayloadDict()`

Adds all the name-value pairs in a dictionary to payloadPairs.

javascript
t.addPayloadDict({
 key1: 'value1',
 key2: 'value2'
});

`resetPayloadPairs()`

Creates a new dictionary of payload pairs, removing all pre-existing name-value pairs. If no argument is provided, creates an empty dictionary.

javascript
t.resetPayloadPairs({
 key1: 'value1',
 key2: 'value2'
});

Other setter methods

For convenience, other setter methods are provided for certain fields. They all use addPayloadPair.

Method name	Key added	Example
`setTrackerVersion`	`tv`	`t.setTrackerVersion('js-3.0.0');`
`setTrackerNamespace`	`tna`	`t.setTrackerNamespace('cloudfront-1');`
`setAppId`	`aid`	`t.setAppId('my-node-application');`
`setPlatform`	`p`	`t.setPlatform('web');`
`setUserId`	`uid`	`t.setUserId('user-427')`
`setScreenResolution`	`res`	`t.setScreenResolution(800, 600)`
`setViewport`	`vp`	`t.setViewport(307,250)`
`setColorDepth`	`cd`	`t.setColorDepth(24)`
`setTimezone`	`tz`	`t.setTimezone('Europe/London')`
`setIpAddress`	`ip`	`t.setIpAddress('37.347.12.457')`

Example usage

Some calls to setter methds, along with comments indicating the current state of the payloadPairs dictionary:

javascript
var snowplowTrackerCore = require('snowplow-tracker-core');
var t = snowplowTrackerCore(); // {}
t.addPayloadPair('a', 'one');  // {a: 'one'}
t.addPayloadDict({
 b: 'two',
 c: 'three'
});                            // {a: 'one', b: 'two', c: 'three'}
t.resetPayloadPairs();         // {}
t.setPlatform('srv');          // {p: 'srv'}
t.setPlatform('pc');           // {p: 'pc'}
t.setViewport(600, 400);       // {p: 'pc', 'vp': 600x400}
t.resetPayloadPairs({
 d: 'four',
 e: 'five'
});                            // {d: 'four', e: 'five'}

4. Tracking methods

Common features

Any method whose name starts with "track..." is a tracking method which creates a payload for a single Snowplow event. The tracking methods have certain features in common.

Custom contexts

Each tracking method's penultimate argument is an optional array of custom context dictionaries.

Example:

javascript
var myContexts = [{
  'schema': 'iglu:com.acme/viewed_product/1-0-1',
  'data': {
    'price': 13,
    'name': 'cyan paint'
  }
},
{
  'schema': 'iglu:com.acme/page_type/1-0-1',
  'data': {
    'type': 'testPage'
  }
}];

t.trackScreenView('title screen', 's-1342', myContexts);

Timestamp argument

Each tracking method's final argument is an optional timestamp. It should be in milliseconds since the Unix epoch - the same format generated by new Date().getTime(). If you don't provide a timestamp for an event, the current time will be used.

Return values

When called, a tracker method will assemble a payload dictionary based on the arguments passed to it and the payloadPairs object, and will add a version 4 UUID. If you provided a callback function when constructing the core instance, that function will be passed the payload. (For example, the callback could be used to convert the payload to a querystring and send it to a Snowplow collector.) The payload will then be returned.

`trackScreenView()`

Argument	Description	Required?	Type
`name`	Human-readable name for this screen	No	Non-empty string
`id`	Unique identifier for this screen	No	String
`context`	Custom context	No	Array
`tstamp`	When the screen was viewed	No	Positive integer

name and id are not individually required, but you must provide at least one of them.

Example:

javascript
t.trackScreenView("HUD > Save Game", "screen23", null, 1368725287000);

`trackPageView()`

Argument	Description	Required?	Type
`pageUrl`	The URL of the page	Yes	Non-empty string
`pageTitle`	The title of the page	No	String
`referrer`	The address which linked to the page	No	String
`context`	Custom context	No	Array
`tstamp`	When the screen was viewed	No	Positive integer

Example:

javascript
t.trackPageView("www.example.com", "example", "www.referrer.com");

`trackEcommerceTransaction()`

Argument	Description	Required?	Type
`orderId`	ID of the eCommerce transaction	Yes	Non-empty string
`affiliation`	Transaction affiliation	No	String
`totalValue`	Total transaction value	Yes	Number
`taxValue`	Transaction tax value	No	Number
`shipping`	Delivery cost charged	No	Number
`city`	Delivery address city	No	String
`state`	Delivery address state	No	String
`country`	Delivery address country	No	String
`currency`	Currency	No	String
`context`	Custom context	No	Array
`tstamp`	When the transaction event occurred	No	Positive integer

Example:

javascript
t.trackEcommerceTransaction(
    "order-456",       // order ID
    null,              // affiliation
    142,               // total
    20,                // tax
    12.99,             // shipping
    "London",          // city
    null,              // state
    "United Kingdom",  // country
    "GBP"              // currency
);

`trackEcommerceTransactionItem()`

Field	Description	Required?	Type
`orderId`	ID of the eCommerce transaction	Yes	Non-empty string
`sku`	Item SKU	Yes	Non-empty string
`name`	Item name	No	String
`category`	Item category	No	String
`price`	Item price	Yes	Number
`quantity`	Item quantity	Yes	Int
`currency`	Currency	No	String
`context`	Custom context for the event	No	Array
`tstamp`	When the transaction event occurred	No	Positive integer

Example:

javascript
t.trackEcommerceTransactionItem(
    "order-456", // order ID
    "570634",    // SKU
    "red hat",   // name
    "headgear",  // category
    10,          // price
    1,           // quantity
    "GBP"        // currency
);

`trackStructEvent()`

Argument	Description	Required?	Type
`category`	The grouping of structured events which this `action` belongs to	Yes	Non-empty string
`action`	Defines the type of user interaction which this event involves	Yes	Non-empty string
`label`	A string to provide additional dimensions to the event data	No	String
`property`	A string describing the object or the action performed on it	No	String
`value`	A value to provide numerical data about the event	No	Number
`context`	Custom context for the event	No	Array
`tstamp`	When the structured event occurred	No	Positive integer

Example:

javascript
t.trackStructEvent("shop", "add-to-basket", null, "pcs", 2);

`trackUnstructEvent()`

Argument	Description	Required?	Type
`properties`	The properties of the event	Yes	JSON
`context`	Custom context for the event	No	Array
`tstamp`	When the unstructured event occurred	No	Positive integer

Example:

javascript
t.trackUnstructEvent({
  "schema": "com.example_company/save-game/jsonschema/1.0.2",
  "data": {
    "save_id": "4321",
    "level": 23,
    "difficultyLevel": "HARD",
    "dl_content": true
  }
})

`trackLinkClick()`

Field	Description	Required?	Type
`targetUrl`	URL of the link	Yes	Non-empty string
`elementId`	HTML id of the link element	No	Non-empty string
`elementClasses`	HTML classes of the link element	No	Array
`elementTarget`	HTML target of the link element	No	String
`context`	Custom context for the event	No	Array
`tstamp`	Item price	No	Number

javascript
t.trackLinkClick(
    'http://www.example.com',  // URL
    'first header',            // id
    ['header'],                // classes
    '_blank'                   // target
);

`trackAdImpression()`

Name	Description	Required?	Type
`impressionId`	Identifier for the particular impression instance	No	string
`costModel`	The cost model for the campaign: 'cpc', 'cpm', or 'cpa'	No	string
`cost`	Ad cost	No	number
`targetUrl`	The destination URL	No	string
`bannerId`	Adserver identifier for the ad banner (creative) being displayed	No	string
`zoneId`	Adserver identifier for the zone where the ad banner is located	No	string
`advertiserID`	Adserver identifier for the advertiser which the campaign belongs to	No	string
`campaignId`	Adserver identifier for the ad campaign which the banner belongs to	No	string

Example:

javascript
t.trackAdImpression(
    '67965967893',             // impressionId
    'cpm',                     // costModel - 'cpa', 'cpc', or 'cpm'
     5.5,                      // cost
    'http://www.example.com',  // targetUrl
    '23',                      // bannerId
    '7',                       // zoneId
    '201',                     // advertiserId
    '12'                       // campaignId
);

`trackAdClick()`

Name	Description	Required?	Type
`targetUrl`	The destination URL	Yes	string
`clickId`	Identifier for the particular click instance	No	string
`costModel`	The cost model for the campaign: 'cpc', 'cpm', or 'cpa'	No	string
`cost`	Ad cost	No	number
`bannerId`	Adserver identifier for the ad banner (creative) being displayed	No	string
`zoneId`	Adserver identifier for the zone where the ad banner is located	No	string
`advertiserID`	Adserver identifier for the advertiser which the campaign belongs to	No	string
`campaignId`	Adserver identifier for the ad campaign which the banner belongs	No	to	string

Example:

javascript
t.trackAdClick(
    'http://www.example.com',  // targetUrl
    '12243253',                // clickId
    'cpm',                     // costModel
     2.5,                      // cost
    '23',                      // bannerId
    '7',                       // zoneId
    '67965967893',             // impressionId - the same as in trackAdImpression
    '201',                     // advertiserId
    '12'                       // campaignId
);

`trackAdConversion()`

Name	Description	Required?	Type
`conversionId`	Identifier for the particular conversion instance	No	string
`costModel`	The cost model for the campaign: 'cpc', 'cpm', or 'cpa'	No	string
`cost`	Ad cost	No	number
`category`	Conversion category	No	number
`action`	The type of user interaction, e.g. 'purchase'	No	string
`property`	Describes the object of the conversion	No	string
`initialValue`	How much the conversion is initially worth	No	number
`advertiserID`	Adserver identifier for the advertiser which the campaign belongs to	No	string
`campaignId`	Adserver identifier for the ad campaign which the banner belongs to	No	string

Example:

javascript
t.trackAdConversion(
    '743560297', // conversionId
    10,          // cost
    'ecommerce', // category
    'purchase',  // action
    '',          // property
    99,          // initialValue - how much the conversion is initially worth
    '201',       // advertiserId
    'cpa',       // costModel
    '12'         // campaignId
);

`trackConsentGranted()`

Name	Description	Required?	Type
`id`	Identifier for the document granting consent	Yes	Number
`version`	Version of the document granting consent	Yes	Number
`name`	Name of the document granting consent	No	String
`description`	Description of the document granting consent	No	String
`expiry`	Date-time string specifying when consent document expires	No	String
`context`	Custom context for the event	No	Array
`tstamp`	When the event occurred	No	Positive integer

Example:

javascript
t.trackConsentGranted(
    743560297,                     // id
    10,                            // version
    'consent-document',            // name
    'a document granting consent', // description
    '2020-11-21T08:00:00.000Z'     // expiry
);

`trackConsentWithdrawn()`

Name	Description	Required?	Type
`id`	Identifier for the document withdrawing consent	Yes	Number
`version`	Version of the document withdrawing consent	Yes	Number
`name`	Name of the document withdrawing consent	No	String
`description`	Description of the document withdrawing consent	No	String
`all`	Specifies whether all consent should be withdrawn	No	Boolean
`context`	Custom context for the event	No	Array
`tstamp`	When the event occurred	No	Positive integer

Example:

javascript
t.trackConsentWithdrawn(
    743560297,                        // id
    10,                               // version
    'consent-document',               // name
    'a document withdrawing consent', // description
    'false'                           // all
);

1. Setup​

Compatibility​

Installation​

2. Initialization​

Requiring the module​

Creating a tracker core instance​

3. Setter methods​

addPayloadPair()​

addPayloadDict()​

resetPayloadPairs()​

Other setter methods​

Example usage​

4. Tracking methods​

Common features​

Custom contexts​

Timestamp argument​

Return values​

trackScreenView()​

trackPageView()​

trackEcommerceTransaction()​

trackEcommerceTransactionItem()​

trackStructEvent()​

trackUnstructEvent()​

trackLinkClick()​

trackAdImpression()​

trackAdClick()​

trackAdConversion()​

trackConsentGranted()​

trackConsentWithdrawn()​

Want to see a custom demo?

1. Setup

Compatibility

Installation

2. Initialization

Requiring the module

Creating a tracker core instance

3. Setter methods

`addPayloadPair()`

`addPayloadDict()`

`resetPayloadPairs()`

Other setter methods

Example usage

4. Tracking methods

Common features

Custom contexts

Timestamp argument

Return values

`trackScreenView()`

`trackPageView()`

`trackEcommerceTransaction()`

`trackEcommerceTransactionItem()`

`trackStructEvent()`

`trackUnstructEvent()`

`trackLinkClick()`

`trackAdImpression()`

`trackAdClick()`

`trackAdConversion()`

`trackConsentGranted()`

`trackConsentWithdrawn()`