[Cache_files_to_browser]#Uint8Array_to_text #text_to_Blob

文件离线or缓存到浏览器.js

  function fileSaveLocal(fileUrl = 'https://cdn.jsdelivr.net/npm/[email protected]/dist/localforage.min.js',
     name = '未命名',
     type = 'text/txt') {
     let blobUrl = null
     let isHave = localStorage.getItem(name)

     function getData() {
         let txtData = localStorage.getItem(name)
         let u = new Uint8Array(JSON.parse(txtData))
         let b = new Blob([u.buffer], {
             type: type
         })
         blobUrl = URL.createObjectURL(b)
     }

     async function fetchData() {
         await fetch(fileUrl)
             .then(d => d.arrayBuffer())
             .then(d => [...new Uint8Array(d)])
             .then(d => {
                 localStorage.setItem(name, JSON.stringify(d))
             })
     }
     if (isHave) {
         getData()
         console.log('本地已存在');
     } else {
         fetchData()
         getData()
         console.log('请求后存储', data);
     }
     return blobUrl
 }