Once again, SharePoint Online prove it is an interesting tool and, more important, it doesn’t necessary leave behind old technologies, as most developers are thinking. If developers are thinking old custom forms are dead, they might be wrong, as Microsoft provides now an easier method to create them. We will consider here creation of a custom new form in SharePoint Online.
Open the site in SharePoint Designer, navigate to lists, right click on the specified and you will see properties window. In forms section, there is a “New” button you need to click.
You need to click on need to see the window where you enter the details for the new custom form.
And now, if you open the new created page in SharePoint Designer you will see the big surprize: IT IS A DATAFORMWEBART. This means you can still do XSLT customization. So you can still develop forms using technology you already know.