---
layout: null
---
let version = "{{site.time | date: "%Y%m%d%H%M%S"}}"
let baseUrl = '{{site.baseurl}}'

// let version = '001'
// let baseUrl = ''

let cachePrefix = 'blog_'
let cacheKey = cachePrefix + version

// 不设置skipWaiting，更新后进入wating状态，依旧是旧的service-worker生效，直到旧的不控制任何 client，比如关闭浏览器，此时再打开页面才会生效
// 设置skipWaiting后，立即成效，这时候会出现一个页面由sw-v1控制，后面又变成sw-v2控制，自己的程序要处理好使用不同sw版本的情况
self.skipWaiting()

self.addEventListener('install', function (event) {
  console.log('serviceWorker install')
  event.waitUntil(
    fetch(baseUrl + '/index.html')
      .then(resp => resp.text())
      .then(html => {
        let reg = /(href|src)=\"(.+?)\"/g // 匹配链接
        let reg2 = /#.*/ // 去除hash
        let urls = []
        let match
        while ((match = reg.exec(html)) !== null) {
          urls.push(match[2])
        }
        urls = urls.map(url => url.replace(reg2, ''))
        urls = urls.filter(url => !url.startsWith('http') && url.startsWith(baseUrl))
        urls = Array.from(new Set(urls))

        caches.open(cacheKey).then(function (cache) {
          cache.addAll(urls)
        })
      })
  )
})

// fetch根据的是cacheKey进行分组，无需等待event.waitUntil
self.addEventListener('activate', function (event) {
  console.log('serviceWorker activate')

  caches.keys().then(keys => {
    keys.forEach(key => {
      if (key.startsWith(cachePrefix) && key != cacheKey) caches.delete(key)
    })
  })
})

this.addEventListener('fetch', function (event) {
  if (new URL(event.request.url).origin != self.origin) {
    return
  }
  event.respondWith(
    caches
      .open(cacheKey)
      .then(cache => cache.match(event.request))
      .then(data => {
        if (data) return data
        return fetch(event.request)
      })
  )
})