Read a cell as the text a reader should hear, and as the key a category is grouped by.
formattedValue wins because it carries the worksheet's own number and date formatting, which is what a sighted reader sees on the axis.
formattedValue
The cell, or undefined for an unmatched column.
undefined
The category key; the empty string for a gap, never a fabricated label such as "null".
"null"
Read a cell as the text a reader should hear, and as the key a category is grouped by.
formattedValuewins because it carries the worksheet's own number and date formatting, which is what a sighted reader sees on the axis.