Add XHR2 fallback if fetch API is not available.

This adds support to parse meta data for images loaded via URL for Internet Explorer 10+.

Author: blueimp

js/load-image-fetch.js

@@ -28,7 +28,7 @@
   if (typeof fetch !== 'undefined' && typeof Request !== 'undefined') {
     loadImage.fetchBlob = function(url, callback, options) {
       if (loadImage.hasMetaOption(options)) {
-        return fetch(new Request(url, options))
+        fetch(new Request(url, options))
           .then(function(response) {
             return response.blob()
           })
@@ -37,8 +37,39 @@
             console.log(err) // eslint-disable-line no-console
             callback()
           })
+      } else {
+        callback()
+      }
+    }
+  } else if (
+    // Check for XHR2 support:
+    typeof XMLHttpRequest !== 'undefined' &&
+    typeof ProgressEvent !== 'undefined'
+  ) {
+    loadImage.fetchBlob = function(url, callback, options) {
+      if (loadImage.hasMetaOption(options)) {
+        // eslint-disable-next-line no-param-reassign
+        options = options || {}
+        var req = new XMLHttpRequest()
+        req.open(options.method || 'GET', url)
+        if (options.headers) {
+          Object.keys(options.headers).forEach(function(key) {
+            req.setRequestHeader(key, options.headers[key])
+          })
+        }
+        req.withCredentials = options.credentials === 'include'
+        req.responseType = 'blob'
+        req.onload = function() {
+          callback(req.response)
+        }
+        req.onerror = req.onabort = req.ontimeout = function(e) {
+          console.log(e) // eslint-disable-line no-console
+          callback()
+        }
+        req.send(options.body)
+      } else {
+        callback()
       }
-      callback()
     }
   }
 })

test/test.js

@@ -875,7 +875,10 @@
     })
   })
 
-  if ('fetch' in window && 'Request' in window) {
+  if (
+    ('fetch' in window && 'Request' in window) ||
+    ('XMLHttpRequest' in window && 'ProgressEvent' in window)
+  ) {
     describe('Fetch', function() {
       it('Should fetch image URL as blob if meta option is true', function(done) {
         expect(