The mark() method creates a named PerformanceMark object representing a high resolution timestamp marker in the browser's performance timeline.

name

A string representing the name of the mark. Must not be the same name as one of the properties of the deprecated PerformanceTiming interface.

markOptions Optional

An object for specifying a timestamp and additional metadata for the mark.

detail Optional

Arbitrary metadata to include in the mark. Defaults to null. Must be structured-cloneable.

startTime Optional

DOMHighResTimeStamp to use as the mark time. Defaults to performance.now().

The PerformanceMark entry that was created.

• SyntaxError: Thrown if the name is one of the properties of the deprecated PerformanceTiming interface. See the example below.
• TypeError: Thrown if startTime is negative.

The following example uses mark() to create named PerformanceMark entries. You can create several marks with the same name. You can also assign them, to have a reference to the PerformanceMark object that has been created.

performance.mark("login-started");
performance.mark("login-started");
performance.mark("login-finished");
performance.mark("form-sent");

const videoMarker = performance.mark("video-loaded");

The performance mark is configurable using the markOptions object where you can put additional information in the detail property, which can be of any type.

performance.mark("login-started", {
  detail: "Login started using the login button in the top menu.",
});

performance.mark("login-started", {
  detail: { htmlElement: myElement.id },
});

The default timestamp of the mark() method is performance.now(). You can set it to a different time using the startTime option in markOptions.

performance.mark("start-checkout", {
  startTime: 20.0,
});

performance.mark("login-button-pressed", {
  startTime: myEvent.timeStamp,
});

Note in order to maintain backwards compatibility, names that are part of the deprecated PerformanceTiming interface can't be used. The following example throws:

performance.mark("navigationStart");
// SyntaxError: "navigationStart" is part of
// the PerformanceTiming interface,
// and cannot be used as a mark name