provide ISO8601 time format

docs/api.md

@@ -807,6 +807,7 @@ The `pino.stdTimeFunctions` object provides a very small set of common functions
 * `pino.stdTimeFunctions.epochTime`: Milliseconds since Unix epoch (Default)
 * `pino.stdTimeFunctions.unixTime`: Seconds since Unix epoch
 * `pino.stdTimeFunctions.nullTime`: Clears timestamp property (Used when `timestamp: false`)
+* `pino.stdTimeFunctions.isoTime`: ISO 8601-formatted time in UTC
 
 * See [`timestamp` option](#opt-timestamp)
 

lib/time.js

@@ -6,4 +6,6 @@ const epochTime = () => `,"time":${Date.now()}`
 
 const unixTime = () => `,"time":${Math.round(Date.now() / 1000.0)}`
 
-module.exports = { nullTime, epochTime, unixTime }
+const isoTime = () => `,"time":"${new Date(Date.now()).toISOString()}"` // using Date.now() for testability
+
+module.exports = { nullTime, epochTime, unixTime, isoTime }

test/timestamp.test.js

@@ -11,6 +11,7 @@ test('pino exposes standard time functions', async ({ ok }) => {
   ok(pino.stdTimeFunctions.epochTime)
   ok(pino.stdTimeFunctions.unixTime)
   ok(pino.stdTimeFunctions.nullTime)
+  ok(pino.stdTimeFunctions.isoTime)
 })
 
 test('pino accepts external time functions', async ({ is }) => {
@@ -101,3 +102,20 @@ test('pino.stdTimeFunctions.unixTime returns seconds based timestamps', async ({
   is(result.time, 1531069920)
   Date.now = now
 })
+
+test('pino.stdTimeFunctions.isoTime returns ISO 8601 timestamps', async ({ is }) => {
+  const opts = {
+    timestamp: pino.stdTimeFunctions.isoTime
+  }
+  const stream = sink()
+  const instance = pino(opts, stream)
+  const ms = 1531069919686
+  const now = Date.now
+  Date.now = () => ms
+  const iso = new Date(ms).toISOString()
+  instance.info('foobar')
+  const result = await once(stream, 'data')
+  is(result.hasOwnProperty('time'), true)
+  is(result.time, iso)
+  Date.now = now
+})