andarist / detect-passive-events

Detect if the browser supports passive event listeners

Detect Passive Events

Detect if the browser supports passive event listeners.

Live detection test

Exports a reference to a singleton object (a micro state machine with an update function) with its state set to if the browser supports passive event listeners, as well as an update() function which re-runs the tests and updates the object's state.

Note that the code used in the detection is adapted from this Passive Events Explainer.

detectPassiveEvents micro state machine

const detectPassiveEvents = {
  hasSupport: boolean,

  // re-run the detection tests and update state
  update() {...},
}

Installing detect-passive-events

$ npm install detect-passive-events

Using detect-passive-events

import detectPassiveEvents from 'detect-passive-events';

// passive events are supported by the browser
if (detectPassiveEvents.hasSupport === true) {
  // set listeners like this
  document.addEventListener('scroll', handleScroll, { capture: false, passive: true });
}

// passive events are not supported by the browser
if (detectPassiveEvents.hasSupport === false) {
  // set listeners like this
  document.addEventListener('scroll', handleScroll, false);
}

// updating the state - most apps won't need to use this at all
detectPassiveEvents.update();

Note that the update() function is run once at the time of import to set the object's initial state, and generally doesn't need to be run again. If it doesn't have access to the window, then the state will be undefined (detect-passive-events will not throw an error), and you will need to call the update() function manually at a later time to update its state.

Part of the detect-it family

• detect-it
  • detect-hover
  • detect-pointer
  • detect-touch-events
  • detect-passive-events