Limited support Use with care and provide a fallback when broad support matters.

CPU compute pressure

Experimental: This is an experimental technology

Check the Browser compatibility table carefully before using this in production.

Note: This feature is available in Web Workers, except for Service Workers.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The PressureObserver interface is part of the Compute Pressure API and is used to observe the pressure changes of system resources such as the CPU.

Device APIs

Browser support

Feature Desktop Mobile
Chrome
Edge
Firefox
Safari
Chrome Android
Safari iOS
PressureObserver
Experimental
125
125
disconnect
Experimental

The disconnect() method of the PressureObserver interface stops the pressure observer callback from receiving pressure records from all sources.
125
125
knownSources_static
Experimental

The static knownSources read-only property of the PressureObserver interface returns an array of the PressureRecord.source values supported by the user agent in alphabetical order.
125
125
observe
Experimental

The observe() method of the PressureObserver interface tells the pressure observer to start observing pressure changes. After this method is called, the observer will call its callback function when a pressure record for the specified source is observed.
125
125
PressureObserver
Experimental

The PressureObserver() constructor creates a new PressureObserver object to watch for changes to pressure changes of system resources such as the CPU.
125
125
takeRecords
Experimental

The takeRecords() method of the PressureObserver interface returns the current list of pressure records stored in the pressure observer, emptying it out.
125
125
unobserve
Experimental

The unobserve() method of the PressureObserver interface stops the pressure observer callback from receiving pressure records from the specified source.
125
125
PressureRecord
Experimental

The PressureRecord interface is part of the Compute Pressure API and describes the pressure trend of a source at a specific moment of transition.
125
125
source
Experimental

The read-only source property is a string indicating the origin source from which the record is coming.
125
125
state
Experimental

The read-only state property is a string indicating the pressure state recorded.
125
125
time
Experimental

The read-only time property returns the DOMHighResTimeStamp recorded for a PressureRecord. It corresponds to the time the data was obtained from the system relative to the time origin of the global object in which the PressureObserver generated the notification.
125
125
toJSON
Experimental

The toJSON() method is a Serialization; it returns a JSON representation of the PressureRecord object.
125
125
Other
html.elements.iframe.allow.compute-pressure
Experimental
125
125
http.headers.Permissions-Policy.compute-pressure
Experimental

The HTTP Permissions-Policy header compute-pressure directive controls access to the Compute Pressure API.
125
125
1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)

Syntax

JAVASCRIPT 
const observer = new PressureObserver((records) => {
  for (const record of records) {
    console.log('CPU state:', record.state); // 'nominal'|'fair'|'serious'|'critical'
  }
});
observer.observe('cpu', { sampleInterval: 1000 });

Use cases

  • Use CPU compute pressure

    Use CPU compute pressure when standard HTML needs a more specific platform feature, semantic signal, or browser capability.

  • Handle edge cases

    Apply CPU compute pressure to solve a focused requirement without redesigning the whole page architecture.

Cautions

  • Test CPU compute pressure in your target browsers and input environments before depending on it as a primary behavior.
  • Provide a fallback path or acceptable degradation strategy when support is still limited.

Accessibility

  • Make sure CPU compute pressure supports the intended task without making the page harder to perceive, understand, or operate.

Related links