new VisibilityChangeEmitter()
Listen to page visibility change events (i.e. when the page is focused / blurred) by an event emitter.
Warning: This does not work on all browsers, but should work on all modern browsers
Example
const myVisibilityEmitter = new VisibilityChangeEmitter(); myVisibilityEmitter.on('visibilityChange', (pageInFocus) => { if ( pageInFocus ){ // Page is in focus console.log('In focus'); } else { // Page is blurred console.log('Out of focus'); } }); // To access the visibility state directly, call: console.log('Am I focused now? ' + myVisibilityEmitter.isVisible());