> ## Documentation Index > Fetch the complete documentation index at: https://developers.everflow.io/llms.txt > Use this file to discover all available pages before exploring further. # Click Tracking > Record clicks and generate transaction IDs using the Everflow JavaScript SDK. The `EF.click()` method records a click event and returns a Promise that resolves with the transaction ID. This transaction ID can then be used for conversion attribution. ## Basic Usage ```javascript theme={null} EF.click({ offer_id: 1, affiliate_id: 1 }); ``` ## Parameters Which fields are required depends on how the click is identified — see [How a click is identified](#how-a-click-is-identified) below. All other fields are optional. | Parameter | Type | Required | Description | | ----------------- | ------- | ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------- | | `offer_id` | integer | Conditional | The offer identifier — required to record a **new** click (direct linking) | | `affiliate_id` | integer | Conditional | Required to record a **new** click — unless the affiliate is supplied by a `coupon_code`, or an existing click is matched via `transaction_id` | | `uid` | integer | No | Offer URL ID (extra destination URL) | | `creative_id` | integer | No | Creative identifier | | `sub1` – `sub10` | string | No | Affiliate sub-placement tracking values | | `adv1` – `adv10` | string | No | Advertiser sub-parameter values | | `source_id` | string | No | Traffic source identifier | | `coupon_code` | string | Conditional | A coupon code — records a click attributed via the coupon's offer and affiliate | | `cost` | number | No | Media-buying cost to attribute to this click | | `fbclid` | string | No | Facebook click ID (auto-detected from the URL if omitted) | | `gclid` | string | No | Google click ID (auto-detected from the URL if omitted) | | `ttclid` | string | No | TikTok click ID (auto-detected from the URL if omitted) | | `sccid` | string | No | Snapchat click ID (auto-detected from the URL if omitted) | | `transaction_id` | string | Conditional | A 32-character transaction ID — matches an **existing** click instead of creating one (ITP workaround) | | `tracking_domain` | string | No | Tracking domain override (for multi-tenant setups — see [Configuration](/sdk/configuration#multi-account-tracking-tracking_domain)) | | `parameters` | object | No | Free-form custom key–value parameters | | `do_not_track` | boolean | No | When `true`, the call resolves immediately without recording a click | ### How a click is identified `EF.click()` resolves to one of three behaviors depending on which identifier you pass. Provide the fields for the mode you need: * **New click (direct linking)** — requires **both** `offer_id` and an affiliate identity (`affiliate_id`). If either is missing, the server records the click with an error code and returns no transaction ID — the promise resolves with an empty string. This is what most recipes do. * **Existing click (ITP workaround)** — pass a valid **32-character** `transaction_id` (typically read from `_ef_transaction_id` after a redirect tracking link). The SDK matches the click that already exists and reinforces its first-party cookie; `offer_id` and `affiliate_id` are not needed and are ignored in this mode. If the ID is missing, malformed, or not found, the call falls back to recording a new click — which then requires `offer_id`. * **Coupon attribution** — pass `coupon_code`; the offer and affiliate are resolved from the coupon assignment. The 32-character length matters: a `transaction_id` that isn't exactly 32 characters is treated as absent, and the call falls through to new-click behavior. **Coupon code takes precedence.** If a valid `coupon_code` arrives alongside `offer_id` and `affiliate_id`, the click is attributed to the **coupon's** offer and affiliate — not the passed `affiliate_id`. Only send a `coupon_code` when you intend coupon-based attribution. ## Return Value `EF.click()` returns a Promise that resolves with the transaction ID: ```javascript theme={null} EF.click({ offer_id: 1, affiliate_id: 1 }).then(function(transactionId) { console.log('Transaction ID:', transactionId); }); ``` The promise **always resolves and never rejects**. On success it resolves with the 32-character transaction ID; when nothing could be tracked — `do_not_track`, no valid identifier, or a server/validation error — it resolves with an **empty string** instead. This is why patterns that chain off the result (cross-site link decoration, the EF-to-EF chain) test `if (transactionId)` and supply a fallback rather than relying on `.catch()`. ## Examples **With sub-placements and URL parameters:** ```javascript theme={null} EF.click({ offer_id: EF.urlParameter('oid'), affiliate_id: EF.urlParameter('affid'), sub1: EF.urlParameter('sub1'), sub2: EF.urlParameter('sub2'), source_id: EF.urlParameter('source') }); ``` `EF.urlParameter()` returns `null` when the parameter is not present in the URL. The SDK skips any optional field whose value is `null` or `undefined`, so a missing URL parameter is simply omitted from the click rather than sent as an empty value. **Parameters after a `#` in the URL are not readable.** `EF.urlParameter()` reads from the URL's query string (`?…`), so anything in the fragment — e.g. `https://example.com/#/path?oid=1&affid=2` — is invisible to it, and the click will be missing those values. This is common with hash-routed single-page apps. If your parameters live after the `#`, move them before it, or read them from `window.location.href` directly instead of `EF.urlParameter()`. **With custom parameters:** ```javascript theme={null} EF.click({ offer_id: 1, affiliate_id: 1, parameters: { campaign_name: 'summer_sale', landing_page: 'variant_b' } }); ``` **All parameters:** A reference call listing every parameter `EF.click()` accepts. In practice you only pass the ones relevant to your setup — optional fields with a `null`/`undefined` value are omitted automatically. ```javascript theme={null} EF.click({ // Core attribution — provide at least one of offer_id, transaction_id, or coupon_code offer_id: EF.urlParameter('oid'), affiliate_id: EF.urlParameter('affid'), transaction_id: EF.urlParameter('_ef_transaction_id'), coupon_code: EF.urlParameter('__cc'), // Optional attribution context uid: EF.urlParameter('uid'), creative_id: EF.urlParameter('creative_id'), source_id: EF.urlParameter('source_id'), // Affiliate sub-parameters (sub1–sub10) sub1: EF.urlParameter('sub1'), sub2: EF.urlParameter('sub2'), sub3: EF.urlParameter('sub3'), sub4: EF.urlParameter('sub4'), sub5: EF.urlParameter('sub5'), sub6: EF.urlParameter('sub6'), sub7: EF.urlParameter('sub7'), sub8: EF.urlParameter('sub8'), sub9: EF.urlParameter('sub9'), sub10: EF.urlParameter('sub10'), // Advertiser sub-parameters (adv1–adv10) adv1: EF.urlParameter('adv1'), adv2: EF.urlParameter('adv2'), adv3: EF.urlParameter('adv3'), adv4: EF.urlParameter('adv4'), adv5: EF.urlParameter('adv5'), adv6: EF.urlParameter('adv6'), adv7: EF.urlParameter('adv7'), adv8: EF.urlParameter('adv8'), adv9: EF.urlParameter('adv9'), adv10: EF.urlParameter('adv10'), // Media-buying cost cost: EF.urlParameter('cost'), // Paid-channel click IDs (auto-detected from the URL if omitted) fbclid: EF.urlParameter('fbclid'), gclid: EF.urlParameter('gclid'), ttclid: EF.urlParameter('ttclid'), sccid: EF.urlParameter('sccid'), // Route this click to a specific Everflow account (overrides the SDK script's domain) tracking_domain: 'www.your-tracking-domain.com', // Free-form custom query parameters parameters: { my_custom_key: 'my_custom_value' }, // Behavior flag do_not_track: false }); ``` ## ITP Workaround and First-Party Cookie Tracking You can combine the SDK with traditional redirect tracking links to enhance attribution on browsers that restrict third-party cookies (Safari ITP, etc.). When a user lands on your owned landing page after going through a redirect link, fire `EF.click()` with the `transaction_id` extracted from the URL — the SDK will set a first-party cookie on your landing-page domain, making subsequent conversion attribution more reliable. Configure your tracking link's destination URL to include the `transaction_id`, `offer_id`, and `affiliate_id` macros. For a destination URL like: ``` https://destination-url.com?transaction_id=af189e77650e4e908af797b61b03ac0b&oid=1&affid=5 ``` fire the SDK click with the extracted values: ```javascript theme={null} EF.click({ offer_id: EF.urlParameter('oid'), affiliate_id: EF.urlParameter('affid'), transaction_id: EF.urlParameter('transaction_id') }); ``` The SDK recognizes the existing `transaction_id` and enhances attribution without creating a duplicate click. ## Advanced Usage ### Preventing duplicate clicks Use `EF.getTransactionId()` to check whether a transaction already exists for the offer before firing a new click — useful when the same page may be loaded multiple times for a returning user: ```javascript theme={null} var offerId = 3; var previousTransactionId = EF.getTransactionId(offerId); if (!previousTransactionId) { EF.click({ offer_id: offerId, affiliate_id: EF.urlParameter('affid') }); } else { // The user already has a transaction for this offer — skip firing a new click } ``` ### Falling back to default values When the URL may not always contain `offer_id` or `affiliate_id` parameters, you can supply default values rather than letting the click fail: ```javascript theme={null} var DEFAULT_OFFER_ID = 1; var DEFAULT_AFFILIATE_ID = 10; var offerId = EF.urlParameter('oid') || DEFAULT_OFFER_ID; var affiliateId = EF.urlParameter('affid') || DEFAULT_AFFILIATE_ID; EF.click({ offer_id: offerId, affiliate_id: affiliateId }); ``` For fleet-wide organic fallback (applied automatically to every SDK call on the page), use [`EF.configure({ organic: {...} })`](/sdk/configuration#organic-tracking) instead of per-call defaults. ### Multi-tenant attribution (multiple Everflow accounts) When multiple Everflow accounts fire clicks on the same page, pass `tracking_domain` per call to route each click to the correct account. See [Multi-account tracking](/sdk/configuration#multi-account-tracking-tracking_domain) for the full pattern and caveats.