# Element Signals

XCE provides a custom Javascript API called  `signal layer`  that gets added to the global namespace when our script is loaded. This is used as an abstraction layer for us to scale a performant integration.

There are three signal types available:  `set` ,  `listen` and  `update`  

These are objects pushed to the signal layer by calling  `signalLayer.push()` . Before calling the signal layer we first must initialize it like so:

```javascript
window.signalLayer = window.signalLayer || [];
```

Each signal object will be conformed by two main properties:

*  `signal`  - Type of signal(`set` ,  `listen` or  `update`)
*  `element`  - The element tag name we want to publish to(`xce-protection-offer`)

Any additional properties will be depending on the signal we are working with, so please see the following guidelines on how to use set, listen and update signals and what their specific attributes are.

{% hint style="warning" %}
Each variable declared within the signal layer object will persist only as long as the visitor remains on the current page.
{% endhint %}

{% hint style="info" %}
See Element manipulation for instructions on passing state between pages to the element
{% endhint %}