blockbench/lib/file_saver.js

/*
* FileSaver.js
* A saveAs() FileSaver implementation.
*
* By Eli Grey, http://eligrey.com
*
* License : https://github.com/eligrey/FileSaver.js/blob/master/LICENSE.md (MIT)
* source  : http://purl.eligrey.com/github/FileSaver.js
*/


// The one and only way of getting global scope in all enviorment
// https://stackoverflow.com/q/3277182/1008999
var _global = (function () {
// some use content security policy to disable eval
  try {
    return Function('return this')() || (42, eval)('this')
  } catch (e) {
    // every global should have circular reference
    // used for checking if someone writes var window = {}; var self = {}
    return typeof window === 'object' && window.window === window ? window
    : typeof self === 'object' && self.self === self ? self
    : typeof global === 'object' && global.global === global ? global : this
  }
})()

function bom (blob, opts) {
  if (typeof opts === 'undefined') opts = { autoBom: false }
  else if (typeof opts !== 'object') {
    console.warn('Depricated: Expected third argument to be a object')
    opts = { autoBom: !opts }
  }

  // prepend BOM for UTF-8 XML and text/* types (including HTML)
  // note: your browser will automatically convert UTF-16 U+FEFF to EF BB BF
  if (opts.autoBom && /^\s*(?:text\/\S*|application\/xml|\S*\/\S*\+xml)\s*;.*charset\s*=\s*utf-8/i.test(blob.type)) {
    return new Blob([String.fromCharCode(0xFEFF), blob], { type: blob.type })
  }
  return blob
}

function download (url, name, opts) {
  var xhr = new XMLHttpRequest()
  xhr.open('GET', url)
  xhr.responseType = 'blob'
  xhr.onload = function () {
    saveAs(xhr.response, name, opts)
  }
  xhr.onerror = function () {
    console.error('could not download file')
  }
  xhr.send()
}

function corsEnabled (url) {
  var xhr = new XMLHttpRequest()
  // use sync to avoid popup blocker
  xhr.open('HEAD', url, false)
  xhr.send()
  return xhr.status >= 200 && xhr.status <= 299
}

// `a.click()` don't work for all browsers (#465)
function click(node) {
  try {
    node.dispatchEvent(new MouseEvent('click'))
  } catch (e) {
    var evt = document.createEvent('MouseEvents')
    evt.initMouseEvent('click', true, true, window, 0, 0, 0, 80,
                          20, false, false, false, false, 0, null)
    node.dispatchEvent(evt)
  }
}

var saveAs = _global.saveAs ||
// probably in some web worker
(typeof window !== 'object' || window !== _global)
  ? function saveAs () { /* noop */ }

// Use download attribute first if possible (#193 Lumia mobile)
: 'download' in HTMLAnchorElement.prototype
? function saveAs (blob, name, opts) {
  var URL = _global.URL || _global.webkitURL
  var a = document.createElement('a')
  name = name || blob.name || 'download'

  a.download = name
  a.rel = 'noopener' // tabnabbing

  // TODO: detect chrome extensions & packaged apps
  // a.target = '_blank'

  if (typeof blob === 'string') {
    // Support regular links
    a.href = blob
    if (a.origin !== location.origin) {
      corsEnabled(a.href)
        ? download(blob, name, opts)
        : click(a, a.target = '_blank')
    } else {
      click(a)
    }
  } else {
    // Support blobs
    a.href = URL.createObjectURL(blob)
    setTimeout(function () { URL.revokeObjectURL(a.href) }, 4E4) // 40s
    setTimeout(function () { click(a) }, 0)
  }
}

// Use msSaveOrOpenBlob as a second approch
: 'msSaveOrOpenBlob' in navigator
? function saveAs (blob, name, opts) {
  name = name || blob.name || 'download'

  if (typeof blob === 'string') {
    if (corsEnabled(blob)) {
      download(blob, name, opts)
    } else {
      var a = document.createElement('a')
      a.href = blob
      a.target = '_blank'
      setTimeout(function () { click(a) })
    }
  } else {
    navigator.msSaveOrOpenBlob(bom(blob, opts), name)
  }
}

// Fallback to using FileReader and a popup
: function saveAs (blob, name, opts, popup) {
  // Open a popup immediately do go around popup blocker
  // Mostly only avalible on user interaction and the fileReader is async so...
  popup = popup || open('', '_blank')
  if (popup) {
    popup.document.title =
    popup.document.body.innerText = 'downloading...'
  }

  if (typeof blob === 'string') return download(blob, name, opts)

  var force = blob.type === 'application/octet-stream'
  var isSafari = /constructor/i.test(_global.HTMLElement) || _global.safari
  var isChromeIOS = /CriOS\/[\d]+/.test(navigator.userAgent)

  if ((isChromeIOS || (force && isSafari)) && typeof FileReader === 'object') {
    // Safari doesn't allow downloading of blob urls
    var reader = new FileReader()
    reader.onloadend = function () {
      var url = reader.result
      url = isChromeIOS ? url : url.replace(/^data:[^;]*;/, 'data:attachment/file;')
      if (popup) popup.location.href = url
      else location = url
      popup = null // reverse-tabnabbing #460
    }
    reader.readAsDataURL(blob)
  } else {
    var URL = _global.URL || _global.webkitURL
    var url = URL.createObjectURL(blob)
    if (popup) popup.location = url
    else location.href = url
    popup = null // reverse-tabnabbing #460
    setTimeout(function () { URL.revokeObjectURL(url) }, 4E4) // 40s
  }
}

//module.exports = _global.saveAs = saveAs.saveAs = saveAs