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"
  }],
  "tags": ["interval", "date", "milliseconds", "epoch"]
}