Deleting and inserting in a single visual block selection

Question

I'm trying to understand how the visual-block mode deals with Backspace and Delete, and if it is possible to vertically select a column of text, delete some characters, then insert new ones in a single selection.

For example, with these 3 lines of code (each proceeded with 2 spaces):

  a = 1;  
  b = 2;  
  c = 3;  

With my cursor on a I press Ctrlvjj selecting all the letters, then I to go into insert mode. At this point I can delete the two preceeding spaces with Backspace then start typing var but when I hit Esc I get the following:

var a = 1;
  r b = 2;
  r c = 3;

I don't understand why Vim is not including the va on the last two lines. I ran some other tests with Backspace and the Delete key and noticed that neither of these actions are applied to other lines, however I would then expect something like:

var a = 1;
  var b = 2;
  var c = 3;

What is the multiline cursor doing that causes va to be overwritten/ignored? Also, I know that I can select the two columns of spaces and delete them with d then reselect the three lines and type var, but is there a way to do this only having to make the selection once?

deletion then insertion

deletion tests

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I've tested this without a vimrc

Answer 1

Instead of deleting with d, select spaces in Visual Block Mode and press c, then type var. Difference is that c performs two operations at once - it deletes text and stays in Insert Mode after that.

As for why Vim is not including va - simply it's outside of the visually selected block. I couldn't find anything about that in the :help, but I think Vim is not extending selection left on Backspace and it doesn't repeat all the keystrokes like in a macro. It just copies text inserted within seleted area and pastes it after to the remaining lines of selection.