QGIS/resources/function_help/json/epoch

{
  "name": "epoch",
  "type": "function",
  "groups": ["Date and Time"],
  "description": "Returns the interval in milliseconds between the unix epoch and a given date value.",
  "arguments": [ {"arg":"date","description":"a date or datetime value"} ],
  "examples": [ { "expression":"epoch(to_date('2017-01-01'))", "returns":"1483203600000"} ]
}