What are some alternatives?
When comparing Gnumeric and dhtmlxSpreadsheet, you can also consider the following products
LibreOffice - Calc - LibreOffice Calc is the spreadsheet program you've always needed. A fork of OpenOffice.
ag-Grid - The best HTML5 datagrid in the world
Microsoft Office Excel - Microsoft Office Excel is a commercial spreadsheet application.
Google Sheets - Synchronizing, online-based word processor, part of Google Drive.
EtherCalc - EtherCalc is a web spreadsheet.