Convert dataframe to javascript matrix.
df2js(dat)
The data frame you want to add the footnote to.
dat <- cbind.data.frame(matrix(LETTERS[1:8], nrow = 4),
matrix(1:8, nrow = 4))
df2js(dat = dat)
#> [["1","2","1","2"],
#> ["A","E","1","5"],
#> ["B","F","2","6"],
#> ["C","G","3","7"],
#> ["D","H","4","8"]]