- With the introduction of the -pre method in DataTables 1.9, the -asc and -desc sorting functions became more or less redundant since they are simple comparisons (all of the complexity is now in the -pre formatting function). As such the call to the -asc / -desc method is overhead that really isn't needed, and this commit introduces a sort function that doesn't call the -asc / -desc methods, instead just doing the comparison itself. In tests, this relatively simple change leads to a performance improvement of around 15% in all browsers (it also has the side benefit of less operations, so IE8- will be able to sort larger tables before flagging up a slow script warning).
- We can't just remove the sorting method which will call -asc / -desc though since not all sorting plug-ins will have a -pre method. Therefore, for backwards compatiblity the old sort function (albeit updated for the changed variables) is retained. The backwards compatibality code adds around 300 bytes to the library, but this is an unaccounced change, so backwards compatiblity must be retained.
- The old sort method will be removed in v1.11. The -asc and -desc methods are now fully depricated.
- Altered the sorting method to flatten the aaSorting array since the introduction of aDataSort in v1.9 required an extra loop in several locations. The functionality is very useful, but the extra loop can be a bit messy and slightly hit performance, so it is now flattened to be a single array (with object information so it makes sense, rather htan array indexes!).
- Altered the order of sorting when building _aSortData since it was looking up the same variable smultiple times which really wasn't needed.
This is part of a small incremental changes plan for DataTables! There are still a huge number of things to improve in this area, but this is a nice clean up and a nice 15% sorting performance improvement to get us started :-).
Note: _fnColumnOrdering is left in place at the moment, although it may be updated as work progresses on 1.10 with regard to the increased use of column names.
Removed: fnRender - fnRender was depricated in 1.9 and is now being completely removed here. Its always been a bit messy and is now superseded by mRender. The main reason for this is that DataTables use to take an independent copy of the input data source object / array. This is a performance hit and it means we can't do any binding to external objects (for example it makes Knockout integration almost impossible).
Removed: bUseRendered - with fnRender being removed, bUseRendered is irrelevent
Updated: With fnRender being removed we no longer need to take an independent copy of the data source object / array (since DataTables itself isn't ever going to write to it now - fnRender did and the copy was included so we didn't inadvertantly change a developers data source object without them knowing about it. This is no longer a problem, and in fact having it use the same data source object is extremely useful in many cases.
Simplify and improve performance
- Only check once for the presence of any sorting class instead of checking for the 3 individual classes
- Use lastIndexOf(str, 0) instead of indexOf
http://jsperf.com/rep-reg-string/4
Use greedy match regex for replacements
Otherwise, you could have:
"_START_ of _TOTAL_, showing _START_ to _END_"
replaced as:
"1 of 5, showing _START_ to 3"
