Attribute: key

The key attribute specifies where to get the value from the specific source as specified in the source attribute.

The following table explains the key attribute for possible values of the source attribute.

Source	Key (usage)	Wiki Link
dom	css selector	Source: dom
expression	js expression	Source: expression
query	name of query parameter	Source: query
cookie	cookie name	Source: cookie
localStorage	localStorage key	Source: localStorage
sessionStorage	sessionStorage key	Source: sessionStorage
extension	name of extension	Source: extention
on-async	expression to async function	Source: on-async
promise	coming soon...

Examples

DOM

{
  "source": "dom",
  "key": "button",
  "action": "event",
  "on": "click",
  "tag": "button.clicked"
}

Expression

{
  "source": "expression",
  "key": "window.data.productName",
  "action": "bind",
  "tag": "product.name"
}

Query

{
  "source": "query",
  "key": "utm_source",
  "action": "bind",
  "tag": "campaign.source"
}

localStorage

{
 "source": "localStorage",
 "key": "logged-in",
 "action": "bind",
 "type": "boolean",
 "tag": "user.logged-in"
}