js下载文件

index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="./js/download.js"></script>
</head>
<body>
  <button onClick="aaa()">下载</button>
</body>
</html>

<script>
  function aaa(){
    download("https://bztic-ross-portal.oss-cn-shanghai.aliyuncs.com/sit/standardModule/ross-taskmanage/1/2122526a9619-467.mp3","双截棍 - 周杰伦.mp3","image/png")
    // download("https://scm-dam.oss-cn-shanghai-internal.aliyuncs.com/sit/standardModule/ross-taskmanage/1/86ac38ee6850-4d1.png","双截棍 - 周杰伦.jpg","image/png")
  }
</script>
download.js(可以直接用)
function download(data, strFileName, strMimeType) {
  var self = window // this script is only for browsers anyway...
  var defaultMime = 'application/octet-stream' // this default mime also triggers iframe downloads
  var mimeType = strMimeType || defaultMime
  var payload = data
  var url =
    typeof payload === 'string' && payload.indexOf('http') === 0 && payload
  var anchor = document.createElement('a')
  var toString = function(a) {
    return String(a)
  }
  var myBlob = self.Blob || self.MozBlob || self.WebKitBlob || toString
  var fileName = strFileName || 'download'
  var blob
  var reader
  myBlob = myBlob.call ? myBlob.bind(self) : Blob

  if (String(this) === 'true') {
    //reverse arguments, allowing download.bind(true, "text/xml", "export.xml") to act as a callback
    payload = [payload, mimeType]
    mimeType = payload[0]
    payload = payload[1]
  }

  if (url && url.length < 2048) {
    // if no filename and no mime, assume a url was passed as the only argument
    anchor.href = url // assign href prop to temp anchor
    if (url && anchor.href) {
      // if the browser determines that it's a potentially valid url path:
      var ajax = new XMLHttpRequest();
      ajax.open("GET", url, true);
      ajax.responseType = 'blob';
      ajax.onload = function(e) {
        download(e.target.response, strFileName, defaultMime);
      };
      setTimeout(function() { ajax.send(); }, 0); // allows setting custom ajax headers using the return:
      return new Promise(function (resolve, reject) {
        resolve(ajax)
      })
      
      // return Vue.prototype.$http
      //   .request({
      //     url,
      //     method: 'get',
      //     responseType: 'blob',
      //     withCredentials: false
      //   })
      //   .then(({ data }) => {
      //     download(data, strFileName, defaultMime)
      //     return data
      //   })
    } // end if valid url?
  } // end if url?

  //go ahead and download dataURLs right away
  if (/^data:([w+-]+/[w+.-]+)?[,;]/.test(payload)) {
    if (payload.length > 1024 * 1024 * 1.999 && myBlob !== toString) {
      payload = dataUrlToBlob(payload)
      mimeType = payload.type || defaultMime
    } else {
      if (navigator.msSaveBlob) {
        // IE10 can't do a[download], only Blobs:
        return navigator.msSaveBlob(dataUrlToBlob(payload), fileName)
      } else {
        // everyone else can save dataURLs un-processed
        return saver(payload)
      }
    }
  } else {
    //not data url, is it a string with special needs?
    if (/([x80-xff])/.test(payload)) {
      var tempUiArr = new Uint8Array(payload.length)
      var mx = tempUiArr.length
      for (var i = 0; i < mx; ++i) {
        tempUiArr[i] = payload.charCodeAt(i)
      }
      payload = new myBlob([tempUiArr], { type: mimeType })
    }
  }
  blob =
    payload instanceof myBlob
      ? payload
      : new myBlob([payload], { type: mimeType })

  function dataUrlToBlob(strUrl) {
    var parts = strUrl.split(/[:;,]/)
    var type = parts[1]
    var decoder = parts[2] === 'base64' ? atob : decodeURIComponent
    var binData = decoder(parts.pop())
    var mx = binData.length
    var uiArr = new Uint8Array(mx)

    for (var i = 0; i < mx; ++i) {
      uiArr[i] = binData.charCodeAt(i)
    }
    return new myBlob([uiArr], { type: type })
  }

  function saver(url, winMode) {
    if ('download' in anchor) {
      //html5 A[download]
      anchor.href = url
      anchor.setAttribute('download', fileName)
      anchor.className = 'download-js-link'
      anchor.innerHTML = 'downloading...'
      anchor.style.display = 'none'
      document.body.appendChild(anchor)
      setTimeout(function() {
        anchor.click()
        document.body.removeChild(anchor)
        if (winMode === true) {
          setTimeout(function() {
            self.URL.revokeObjectURL(anchor.href)
          }, 250)
        }
      }, 66)
      return true
    }

    // handle non-a[download] safari as best we can:
    if (
      /(Version)/(d+).(d+)(?:.(d+))?.*Safari//.test(navigator.userAgent)
    ) {
      if (/^data:/.test(url)) {
        url = 'data:' + url.replace(/^data:([w/-+]+)/, defaultMime)
      }
      if (!window.open(url)) {
        // popup blocked, offer direct download:
        if (
          confirm(
            'Displaying New Document

Use Save As... to download, then click back to return to this page.'
          )
        ) {
          location.href = url
        }
      }
      return true
    }

    //do iframe dataURL download (old ch+FF):
    var f = document.createElement('iframe')
    document.body.appendChild(f)

    if (!winMode && /^data:/.test(url)) {
      // force a mime that will download:
      url = 'data:' + url.replace(/^data:([w/-+]+)/, defaultMime)
    }
    f.src = url
    setTimeout(function() {
      document.body.removeChild(f)
    }, 333)
    return false
  } //end saver

  if (navigator.msSaveBlob) {
    // IE10+ : (has Blob, but not a[download] or URL)
    return navigator.msSaveBlob(blob, fileName)
  }

  if (self.URL) {
    // simple fast and modern way using Blob and URL:
    saver(self.URL.createObjectURL(blob), true)
  } else {
    // handle non-Blob()+non-URL browsers:
    if (typeof blob === 'string' || blob.constructor === toString) {
      try {
        return saver('data:' + mimeType + ';base64,' + self.btoa(blob))
      } catch (y) {
        return saver('data:' + mimeType + ',' + encodeURIComponent(blob))
      }
    }

    // Blob but not URL support:
    reader = new FileReader()
    reader.onload = function(e) {
      saver(this.result)
    }
    reader.readAsDataURL(blob)
  }
  return true
}
 
青云直上三千码
原文地址:https://www.cnblogs.com/djjlovedjj/p/15155909.html