Table Header

<thead> wrapper for children mode. Holds the header row, whose cells are TableHeaderCell. A row must sit inside a section: <table> cannot contain a <tr> directly, because the HTML parser inserts an implied <tbody> when it parses server-rendered markup and React does not when it renders on the client, so the two trees mismatch on hydration. The data-driven data={...} mode renders this element itself whenever columns are supplied; in children mode it is yours to supply.