Performance: mark() method

Note: This feature is available in Web Workers.

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

Syntax

js
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

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

A string which must be set to marker. Identifies as a marker.

color Optional

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

Array of key-value pairs. Values can be any JSON-compatible type.

tooltipText Optional

Short description for tooltip.

startTime Optional

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

Return value

The PerformanceMark entry that was created.

Exceptions

Examples

undefined

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.

js
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.

js
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 performance.now(). You can set it to a different time using the startTime option in markOptions.

js
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:

js
// 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:

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

Specifications