We can pull them apart by indexing and slicing them, and we can join them together by concatenating them. However, we cannot join strings and lists: By contrast, the elements of a list can be as big or small as we like: So lists have the advantage that we can be flexible about the elements they contain, and correspondingly flexible about any downstream processing.
The plan was not ridiculously ambitious. This meant automatic indentation and, if possible at all, syntax highlighting.
In this document I describe the story of implementing this, for your education and amusement. A demonstration of the resulting program, along with the source code, can be found at the project website.
Only indentation The very first attempt merely added auto-indentation to a textarea element. It would scan backwards through the content of the area, starting from the cursor, until it had enough information to decide how to indent the current line.
A statement that is continued to the next line is indented one unit more than the line that starts the statement. When dealing with lists of arguments or the content of array and object literals there are two possible models. If there is any text directly after the opening brace, bracket, or parenthesis, subsequent lines are aligned with this opening character.
If the opening character is followed by a newline optionally with whitespace or comments before itthe next line is indented one unit further than the line that started the list.
And, obviously, if a statement follows another statement it is indented the same amount as the one before it. When scanning backwards through code one has to take string values, comments, and regular expressions which are delimited by slashes into account, because braces and semicolons and such are not significant when they appear inside them.
Even though I was working with just a simple textarea at this point, this was already a bit of a headache.
On W3C-standards-respecting browsers, textarea nodes have selectionStart and selectionEnd properties which nicely give you the amount of characters before the start and end of the selection. Then, there is Internet Explorer.
Internet Explorer also has an API for looking at and manipulating selections. It gives you information such as a detailed map of the space the selected lines take up on the screen, in pixels, and of course the text inside the selection.
It does, however, not give you much of a clue on where the selection is located in the document. After some experimentation I managed to work out an elaborate method for getting something similar to the selectionStart and selectionEnd values in other browsers.
User manual and reference guide version CodeMirror is a code-editor component that can be embedded in Web pages. The core library provides only the editor component, no accompanying buttons, auto-completion, or other IDE functionality.
It does provide a rich API on top of which such functionality can be straightforwardly implemented. Jan 24, · Changing Form Input Styles on Focus with jQuery. A lot of forms can be boring and plain, don’t let yours blend in. This tutorial will show you how to spice them up with CSS classes and default values that change according to which form item is selected.
A convenient way to experiment with various background colors, font colors, and font faces is to open three windows: one for the text editor, to modify the page; another for the browser, to display the page; and a third one to display a list of color names.