Sunday, 20 December 2009

A step towards a Comet-based terminal

While I already have a rough and dirty web page that allows text to be entered, sent to the server and then echoed to anyone viewing the page, it isn't really inspiring enough to take any further. It's overly complicated and hacked together by an advanced manner of cut and pasting, from a selection of code found somewhere on the internet. In order to proceed with any project based on the functionality it is supposed to provide, I need a clean replacement for it.


Code does not write itself. Although it was raining today, I needed to find a hook to get myself interested in this project. So, in order to motivate myself to implement a replacement from scratch, I took my inspiration from the AmigaDOS shell.

A thing of marvel, my goal was to get something that looked and appeared to work as close to it as possible.


I had a little trouble getting the text to wrap right. Whenever a word which was longer than the width of the window was entered, the text entry continued off unseen outside the right of the window, resulting in the addition of a horizontal scrollbar. With a little CSS research, this was fixed by adding the following two lines:

  word-wrap:   break-word;
overflow-y: scroll;
There is, I have just noticed, one remaining bug. Because the console text is directly manipulated HTML, consecutive spaces are not displayed. I need to add the following:
  white-space:  pre-wrap
And finally, when you've entered enough lines to bring the vertical scrollbar into play, it doesn't automatically scroll. I still need to look into that.


Eventually, I had to decide whether I was going to concentrate on functionality or the detail of its appearance, and functionality was the obvious winner. In its current state, the terminal supports the following:
  • Dragging the "window".
  • Text entry.
  • Movement of the cursor within the current line being entered.
  • The enter key starting a new line.
  • The backspace key removing the character before the cursor.
  • The del key removing the character under the cursor.
You can try it here.. although at this stage, it has only been tested in Firefox 3.5.5.

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