update XHR (fetch) demo

demos/xhr/README.md

@@ -116,27 +116,20 @@ axios("/upload", {method: "POST", data: fd});
 
 ## fetch
 
-For downloading data, `response.blob()` resolves to a `Blob` object that can be
+For downloading data, `response.arrayBuffer()` resolves to an `ArrayBuffer` that
-converted to `ArrayBuffer` using a `FileReader`:
+can be converted to `Uint8Array` and passed to `XLSX.read`:
 
 ```js
 fetch(url).then(function(res) {
   /* get the data as a Blob */
   if(!res.ok) throw new Error("fetch failed");
-  return res.blob();
+  return res.arrayBuffer();
-}).catch(function(err) {
+}).then(function(ab) {
-  /* error in getting data */
+  /* parse the data when it is received */
-}).then(function(blob) {
+  var data = new Uint8Array(ab);
-  /* configure a FileReader to process the blob */
+  var workbook = XLSX.read(data, {type:"array"});
-  var reader = new FileReader();
-  reader.addEventListener("loadend", function() {
-    /* parse the data when it is received */
-    var data = new Uint8Array(this.result);
-    var workbook = XLSX.read(data, {type:"array"});
 
-    /* DO SOMETHING WITH workbook HERE */
+  /* DO SOMETHING WITH workbook HERE */
-  });
-  reader.readAsArrayBuffer(blob);
 });
 ```
 

demos/xhr/fetch.html

@@ -41,15 +41,11 @@ document.getElementById('outfile').innerHTML = '<a href="' + demo + '.' + book +
 
 fetch(url).then(function(res) {
 	if(!res.ok) throw new Error("fetch failed");
-	return res.blob();
+	return res.arrayBuffer();
-}).then(function(blob) {
+}).then(function(ab) {
-	var reader = new FileReader();
+	var data = new Uint8Array(ab);
-	reader.addEventListener("loadend", function() {
+	var wb = XLSX.read(data, {type:"array"});
-		var data = new Uint8Array(this.result);
+	process_wb(wb);
-		var wb = XLSX.read(data, {type:"array"});
-		process_wb(wb);
-	});
-	reader.readAsArrayBuffer(blob);
 });
 
 document.getElementById('ulbutton').onclick = function() {