performance_measure_name_startmark_endmark.md

<!-- YAML
added: v8.5.0
changes:
  - version: v14.0.0
    pr-url: https://github.com/nodejs/node/pull/32651
    description: Make `startMark` and `endMark` parameters optional.
-->

* `name` {string}
* `startMark` {string} Optional.
* `endMark` {string} Optional.

Creates a new `PerformanceMeasure` entry in the Performance Timeline. A
`PerformanceMeasure` is a subclass of `PerformanceEntry` whose
`performanceEntry.entryType` is always `'measure'`, and whose
`performanceEntry.duration` measures the number of milliseconds elapsed since
`startMark` and `endMark`.

The `startMark` argument may identify any *existing* `PerformanceMark` in the
Performance Timeline, or *may* identify any of the timestamp properties
provided by the `PerformanceNodeTiming` class. If the named `startMark` does
not exist, then `startMark` is set to [`timeOrigin`][] by default.

The optional `endMark` argument must identify any *existing* `PerformanceMark`
in the Performance Timeline or any of the timestamp properties provided by the
`PerformanceNodeTiming` class. `endMark` will be `performance.now()`
if no parameter is passed, otherwise if the named `endMark` does not exist, an
error will be thrown.