why isn't my pwa instalable code example

Example 1: pwa install

buttonInstall.addEventListener('click', (e) => {  // Hide the app provided install promotion  hideMyInstallPromotion();  // Show the install prompt  deferredPrompt.prompt();  // Wait for the user to respond to the prompt  deferredPrompt.userChoice.then((choiceResult) => {    if (choiceResult.outcome === 'accepted') {      console.log('User accepted the install prompt');    } else {      console.log('User dismissed the install prompt');    }  });});

Example 2: pwa install

let deferredPrompt;window.addEventListener('beforeinstallprompt', (e) => {  // Prevent the mini-infobar from appearing on mobile  e.preventDefault();  // Stash the event so it can be triggered later.  deferredPrompt = e;  // Update UI notify the user they can install the PWA  showInstallPromotion();});