PressureObserver: PressureObserver() constructor

Syntax

new PressureObserver(callback)

Parameters

callback

A callback that will be invoked when pressure records are observed. When the callback is invoked, the following parameters are available:

changes

An array containing all PressureRecord objects recorded since the last time the callback was called, or the last time the observer's takeRecords() method was called.

observer

The observer object that is receiving the above records.

Return value

A new PressureObserver object with the specified callback function that will be invoked when PressureObserver.observe() was called to watch pressure changes.

Exceptions

NotAllowedError DOMException

Thrown if the Compute Pressure API is disallowed by a compute-pressure Permissions Policy.

Examples

Log current pressure

This example creates a PressureObserver and takes action whenever there is a pressure change. The sample interval is set to 1000ms, meaning that there will be updates at most every second.

function callback(records) {
  const lastRecord = records[records.length - 1];
  console.log(`Current pressure ${lastRecord.state}`);
  if (lastRecord.state === "critical") {
    // disable video feeds
  } else if (lastRecord.state === "serious") {
    // disable video filter effects
  } else {
    // enable all video feeds and filter effects
  }
}

try {
  const observer = new PressureObserver(callback);
  await observer.observe("cpu", {
    sampleInterval: 1000, // 1000ms
  });
} catch (error) {
  // report error setting up the observer
}

Specifications

Browser compatibility