Textastic only supports syntax definitions and symbol list definitions in TextMate bundles. Commands and snippets are not loaded from bundles because many of them would require a shell environment which is not available on iOS. Textastic uses its own code completion file format which could probably be used to write a code completion definition for Node.js: https://github.com/blach/Textastic-Customization

Search and Replace in Textastic for iPhone and iPad uses the NSRegularExpression class which in turn uses the syntax that is specified by ICU. 

See http://developer.apple.com/library/mac/#documentation/Foundation/Reference/NSRegularExpression_Class/Reference/Reference.html#//apple_ref/doc/uid/TP40009708-CH1-SW53 

and 

http://userguide.icu-project.org/strings/regexp

Textastic supports the same replacement string syntax as TextMate. See http://manual.macromates.com/en/regular_expressions#replacement_string_syntax_format_strings

You can reference captures using $1, $2 etc.

Case foldings and conditional insertions are supported as described in the TextMate manual.

Another user posted a workaround here: http://feedback.textasticapp.com/topic/165187-editing-a-file-and-going-to-another-app-saves-the-file/

I still hope you make this an option :-)
For those of you that don't like the autosave option, you could turn this off just for Textastic with this command in the terminal;
defaults write com.textasticapp.textastic-mac ApplePersistence -bool no
To turn in back on use;
defaults write com.textasticapp.textastic-mac ApplePersistence -bool yes
I've testet this on DP3 of Mavericks, but it should work on Lion/ML. Found it on OSXDaily

Thanks, it will be fixed in the next update. I don't know how I missed that ;)

I've moved it to the Mac forum.

Thanks for the detailed description. The screenshots are very helpful. I'll try to fix this.

You need to escape space characters with "%20" if you reference such a file in an URL.

Can you give me details? Maybe a screenshot?

Thanks, I've forwarded this problem to the UserEcho guys: http://feedback.userecho.com/topic/211526-landscape-mode-on-ipad/

You can search for new lines using \n and tab characters using \t. That's why you need to escape the backslash with \\.

If you disable regular expressions in the search options, you don't need to escape any other characters besides the backslash.