Performance: mark() method

Available in workers

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

Syntax

mark(name)
mark(name, markOptions)

Parameters

• 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.
        • devtools Optional Experimental
          • : Some browsers have use a structured devtools object within the detail object as part of an Extensibility API that surfaces these in custom tracks in performance traces. See the Chrome’s Extensibility API documentation for more information.
            • dataType Experimental
              • : A string which must be set to marker. Identifies as a marker.
            • color Optional Experimental
              • : Defaults to "primary". Must be one of "primary", "primary-light", "primary-dark", "secondary", "secondary-light", "secondary-dark", "tertiary", "tertiary-light", "tertiary-dark", "error".
            • properties Optional Experimental
              • : Array of key-value pairs. Values can be any JSON-compatible type.
            • tooltipText Optional Experimental
              • : Short description for tooltip.

    • startTime Optional

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

Return value

The PerformanceMark entry that was created.

Exceptions

• 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.

Examples

Creating named markers

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");

Creating markers with details

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 },
});

Creating markers with a different start time

The default timestamp of the mark() method is 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,
});

DevTools Extensibility API

For browsers that support the Extensibility API you can use the detail parameter to provide more details in a devtools object that will be used to display this in performance profiles:

// Marker indicating when the processed image was uploaded
performance.mark("Image Upload", {
  detail: {
    devtools: {
      dataType: "marker",
      color: "secondary",
      properties: [
        ["Image Size", "2.5MB"],
        ["Upload Destination", "Cloud Storage"],
      ],
      tooltipText: "Processed image uploaded",
    },
  },
});

Reserved names

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

Specifications

Browser compatibility