Dedup click-ID capture + record capture timestamp

click-id-tracking.js

@@ -1,26 +1,113 @@
-// Persist Google Ads click identifiers (gclid / gbraid / wbraid) from the
+// Persist Google Ads click identifiers (gclid / wbraid / gbraid) from the
 // landing URL into cookies scoped to photon.codes, so conversions can be
 // attributed after the visitor navigates within the site.
 //
 // Mintlify auto-includes any `.js` file in the content directory on every
 // page and runs it once the page is interactive. That captures the initial
 // landing URL, which is all click-ID attribution needs.
+//
+// A single identifier is stored (Google normally provides one). A genuinely
+// new click replaces prior attribution and resets the capture timestamp,
+// while a reload of the same click preserves the original 90-day window.
+
+(() => {
+  const CLICK_ID_KEYS = ['gclid', 'wbraid', 'gbraid']
+  const CLICK_COOKIE_PREFIX = 'photon_'
+  const CAPTURED_AT_COOKIE_NAME = 'photon_ads_click_captured_at'
+  const COOKIE_DOMAIN = 'photon.codes'
+  const COOKIE_MAX_AGE = 90 * 24 * 60 * 60
+  const MAX_CLICK_ID_LENGTH = 512
+  const COOKIE_ATTRIBUTES
+    = `Domain=${COOKIE_DOMAIN}; Path=/; SameSite=Lax; Secure`
+
+  const readCookie = (name) => {
+    const prefix = `${name}=`
+    const pair = document.cookie
+      .split(';')
+      .map(item => item.trim())
+      .find(item => item.startsWith(prefix))
 
-const CLICK_ID_KEYS = ['gclid', 'gbraid', 'wbraid']
-const COOKIE_MAX_AGE = 90 * 24 * 60 * 60
+    if (!pair) {
+      return null
+    }
 
-const params = new URLSearchParams(window.location.search)
+    try {
+      return decodeURIComponent(pair.slice(prefix.length))
+    }
+    catch {
+      return null
+    }
+  }
 
-for (const key of CLICK_ID_KEYS) {
-  const value = params.get(key)
+  const writeCookie = (name, value) => {
+    document.cookie
+      = `${name}=${encodeURIComponent(value)}; `
+        + `Max-Age=${COOKIE_MAX_AGE}; ${
+          COOKIE_ATTRIBUTES}`
+  }
 
-  if (value) {
+  const deleteCookie = (name) => {
     document.cookie
-      = `photon_${key}=${encodeURIComponent(value)}; `
-        + `Domain=photon.codes; `
-        + `Max-Age=${COOKIE_MAX_AGE}; `
-        + `Path=/; `
-        + `SameSite=Lax; `
-        + `Secure`
+      = `${name}=; Max-Age=0; ${
+        COOKIE_ATTRIBUTES}`
   }
-}
+
+  const params = new URLSearchParams(window.location.search)
+
+  let selectedClick = null
+
+  // Google normally provides only one identifier. This order is the
+  // deterministic fallback if a malformed URL contains more than one.
+  for (const key of CLICK_ID_KEYS) {
+    const value = params.get(key)
+
+    if (value && value.length <= MAX_CLICK_ID_LENGTH) {
+      selectedClick = { key, value }
+      break
+    }
+  }
+
+  // Organic/direct visit: preserve any attribution already stored.
+  if (!selectedClick) {
+    return
+  }
+
+  const selectedCookieName
+    = `${CLICK_COOKIE_PREFIX}${selectedClick.key}`
+
+  const isSameClick
+    = readCookie(selectedCookieName) === selectedClick.value
+
+  if (isSameClick) {
+    // Remove stale identifiers of another type, but don't refresh this
+    // click's 90-day lifetime merely because the page was reloaded.
+    for (const key of CLICK_ID_KEYS) {
+      if (key !== selectedClick.key) {
+        deleteCookie(`${CLICK_COOKIE_PREFIX}${key}`)
+      }
+    }
+
+    const existingCapturedAt = Number(
+      readCookie(CAPTURED_AT_COOKIE_NAME),
+    )
+
+    // Migration path for cookies created by the previous script.
+    if (
+      !Number.isFinite(existingCapturedAt)
+      || existingCapturedAt <= 0
+    ) {
+      writeCookie(CAPTURED_AT_COOKIE_NAME, String(Date.now()))
+    }
+
+    return
+  }
+
+  // A genuinely new Google Ads click replaces the previous attribution.
+  for (const key of CLICK_ID_KEYS) {
+    deleteCookie(`${CLICK_COOKIE_PREFIX}${key}`)
+  }
+  deleteCookie(CAPTURED_AT_COOKIE_NAME)
+
+  writeCookie(selectedCookieName, selectedClick.value)
+  writeCookie(CAPTURED_AT_COOKIE_NAME, String(Date.now()))
+})()