Parametrize formattable in loop based on multiple column

Question

I am using the package formattable to format all data.frames of a list of data.frames. For each data.frame, columns are compared with the previous one. Nevertheless as each data.frame contains different periods, the column names are changing. I am looking for a manner to affect the same style to all columns of all data.frames without using column names.

For example, I start with the table below:

library(formattable)

df <- data.frame(2018 = runif(8), 
                 2019 = runif(8), 
                 2020 = runif(8))

tableF <- 
  formattable(df, list(
    `2019`= formatter("span", style = ~ style(color = ifelse(`2019` >`2018`, "green", "red")),
                        ~ icontext(ifelse(`2019` >`2018`,"arrow-up", "arrow-down"), `2019`)),
    `2020`= formatter("span", style = ~ style(color = ifelse(`2020` >`2019`, "green", "red")),
                        ~ icontext(ifelse(`2020` >`2019`,"arrow-up", "arrow-down"), `2020`))
  ))

tableF

But the next table I want to design is the following

df <- data.frame(2018_s1 = runif(8), 
             2018_s2 = runif(8), 
             2019_s1 = runif(8), 
             2019_s2 = runif(8),  
             2020_s1 = runif(8), 
             2020_s2 = runif(8))

Is there a way define a generic style and to affect it to multiple columns? Something like:

target = colnames(df)[-1],
comp.target = colnames(df)[-ncol(df)],
style = ~ style(color = ifelse(target  > comp.target, "green", "red")),
                                ~ icontext(ifelse(target  > comp.target,"arrow-up", "arrow-down"), target ))

Any help would be appreciated.