As you know var_dump() in addition to value show its data type and length.
Is there any way to log its output to
FirePHP does the job well + you can use it while you're developing Ajax.
Sample code:
require_once('FirePHPCore/fb.php'); # add the library
fb($var); #log the variable
fb( var_export($var,true) ); # log the variable with the var_export format
If you're passing an array to it, you can click it from your console and it will open a popup on your screen. You can even expand/collapse arrays and objects.
EDIT:
If you're looking for data types and length, use var_dump().
fb( var_dump( array(
1,
'a',
true
) ) );