minor

Author: iliakan

5-network/09-resume-upload/article.md

@@ -16,18 +16,20 @@ Unfortunately, it won't help us to resume the upload here, as it triggers when t
 
 Maybe it was buffered by a local network proxy, or maybe the remote server process just died and couldn't process them, or it was just lost in the middle and didn't reach the receiver.
 
-So, this event is only useful to show a nice progress bar.
+That's why this event is only useful to show a nice progress bar.
 
-To resume upload, we need to know exactly the number of bytes received by the server. And only the server can tell that.
+To resume upload, we need to know *exactly* the number of bytes received by the server. And only the server can tell that, so we'll make an additional request.
 
 ## Algorithm
 
-1. First, we create a file id, to uniquely identify the file we're uploading, e.g.
+1. First, create a file id, to uniquely identify the file we're going to upload:
     ```js
     let fileId = file.name + '-' + file.size + '-' + +file.lastModifiedDate;
     ```
     That's needed for resume upload, to tell the server what we're resuming.
 
+    If the name or the size or the last modification date changes, then there'll be another `fileId`.
+
 2. Send a request to the server, asking how many bytes it already has, like this:
     ```js
     let response = await fetch('status', {
@@ -42,17 +44,20 @@ To resume upload, we need to know exactly the number of bytes received by the se
 
     This assumes that the server tracks file uploads by `X-File-Id` header. Should be implemented at server-side.
 
+    If the file don't yet exist at the server, then the server response should be `0`
+
 3. Then, we can use `Blob` method `slice` to send the file from `startByte`:
     ```js
     xhr.open("POST", "upload", true);
 
-    // send file id, so that the server knows which file to resume
+    // File id, so that the server knows which file we upload
     xhr.setRequestHeader('X-File-Id', fileId);
-    // send the byte we're resuming from, so the server knows we're resuming
+
+    // The byte we're resuming from, so the server knows we're resuming
     xhr.setRequestHeader('X-Start-Byte', startByte);
 
     xhr.upload.onprogress = (e) => {
-      console.log(`Uploaded ${startByte + e.loaded} of ${startByte + e.total}`);
+      console.log(`Отправлено ${startByte + e.loaded} из ${startByte + e.total}`);
     };
 
     // file can be from input.files[0] or another source
@@ -72,4 +77,6 @@ But you can download it and run locally for the full demonstration:
 
 [codetabs src="upload-resume" height=200]
 
-As you can see, modern networking methods are close to file managers in their capabilities -- control over headers, progress indicator, sending file parts, etc.
+As we can see, modern networking methods are close to file managers in their capabilities -- control over headers, progress indicator, sending file parts, etc.
+
+We can implement resumable upload and much more.