该浏览器不支持ServiceWorkers消息

Question

我在现有的小vuejs项目中实现了manifest.json和serviceworker.js。我想将应用程序添加到android主屏幕。但是在所有平台，chrome70 / windows或android chrome上，我都得到“此浏览器不支持ServiceWorkers”

为什么？

json：

{
  "short_name": "dsdfsdf",
  "name": "Fsdfsdfdf",
  "icons": [
    {
      "src": "icon-48.png",
      "type": "image/png",
      "sizes": "48x48"
    },
    {
      "src": "icon-96.png",
      "type": "image/png",
      "sizes": "96x96"
    },
    {
      "src": "icon-192.png",
      "type": "image/png",
      "sizes": "192x192"
    }
  ],
  "display": "fullscreen",
  "start_url": "index.html"
}

app.js看起来：

'use strict'

+function() {
    if (!('serviceWorker' in navigator)) {
        alert('This Browser does not support ServiceWorkers.')
        return
    }

    if (navigator.serviceWorker.controller) {
        console.info('ServiceWorker runs')
        return
    }

    console.info('Registering ServiceWorker ...')
    navigator.serviceWorker
    .register('./serviceworker.js')
    .catch(function(err) {
        console.error('ServiceWorker has not been registered!', err)
    })
}()

if (location.search)
    if (location.search.slice(1) === 'from_hs')
        document.querySelector('h1').insertAdjacentHTML('afterend', '<h2>Hey, I\'m an app!</h2>')