# Hooks/callbacks ## What are UXWizz callbacks? The UXWizz callbacks or hooks are a way to tap into the client-side UXWizz tracking functionality and listen to specific events. This is useful, for example, if you want to read or forward some UXWizz tracking data to another service. ### Available callbacks * **UST.onLoaded()** * Called as soon as the ust.min.js finishes loading. * **UST.onTrackingStarted() : false | undefined** * Called when all tracking checks passed, meaning that a new session will be created. * This is called before the session was created. * If you want to stop creating this session, return `false` from this function. * **UST.onSessionCreated(clientID: number)** * Called when the UXWizz server create a new session for this client * **clientID**: The integer number ID of the session. * This is called only once per visit for each visitor. * **UST.onPageViewCreated(clientID: number, clientPageID: number)** * Called when a new page has loaded and the server responded with the pageview ID. * **clientID:** The integer ID of the session. * **clientPageID:** The integer ID of the pageview. * This callback is also called once immediately after onSessionCreated (first pageview). * **UST.onDataSent(data: string\[])** * Called whenever tracking data (session recording/heatmap data) is sent to the server. * **data:** An array of data strings sent to the server. \ Each data string is in the format `c=XXX` where `c` is the data type and `XXX` is the data value.\ The data type can be: * **m** - Heatmap movements * Data value is a [Positions string](#positions-string-compressed-format) * **c** - Heatmap clicks * Data value is a [Positions string](#positions-string-compressed-format) * **p** - Partial recording data * Data value is a [Recording string](#recording-string-compressed-format) * **r** - Full recording data (sent when pageview has finished) * Data value is a [Recording string](#recording-string-compressed-format) * x - Recording type * Data is an integer * w - We have a complete recording * Data is 1 (or not set) * s - Skip updating lastActivity * Useful for when we want to update data for a user, without automatically refreshing/increasing the user's session duration. * Data is 1 (or not set) * **i** - clientPageID * Data value is a number * **UST.onTagAdded(tag: string)** * Called when **UST.addTag()** was called and the server responded. * **tag**: The string that has just been added as a tag to the current user. * **UST.onEventAdded(eventData: Event)** * **Added in version 3.5.0** * Called when **UST.addEvent()** was called and the server responded. * **eventData**: The original eventData passed, also containing **clientID** and **clientPageID** * **UST.onGDPRAccepted()** * Called when the user accepted the UXWizz tracking consent pop-up. * **UST.onGDPRDeclined()** * Called when the user declined the UXWizz tracking consent pop-up. ### **Usage example** {% hint style="warning" %} Make sure write the callbacks declarations **after the tracking file** is included. {% endhint %} #### Example: Multiple UXWizz callbacks ```javascript // // After ust.min.js include snippet // ... //