This is a solution that gets rid of the dot that is default were using selected rows in reactable. This code snippet demonstrates a coloured row like that of DataTables for selected elements that gets rid of the dot but runs a bit slower. Thanks #r #shiny #reactable

reactable_selected_row_color_app.R

#
# This is a Shiny web application. You can run the application by clicking
# the 'Run App' button above.
#
# Find out more about building applications with Shiny here:
#
#    http://shiny.rstudio.com/
#

library(shiny)
library(reactable)

# Define UI for application that draws a histogram
ui <- fluidPage(

    # Application title
    titlePanel("This displays highlighting \n rows in reactable without 
               that ugly dot thing"),

    # Sidebar with a slider input for number of bins
    sidebarLayout(
        sidebarPanel(
            shiny::tags$button('custom button w/o bootstrap')
        ),

        # Show a plot of the generated distribution
        mainPanel(
          shiny::tags$section(
          reactableOutput('mytable')
          )
                              
        )
    )
)

# Define server logic required to draw a histogram
server <- function(input, output) {
# // Only handle click events on the 'mb' column
#           if (colInfo.id !== 'mpg') {
#             return
#           }
    onclick_js <- JS(

        "function(rowInfo, colInfo) {


          // Send the click event to Shiny, which will be available in input$show_details
          // Note that the row index starts at 0 in JavaScript, so we add 1
          if (window.Shiny) {
            console.log(rowInfo)
            console.log(colInfo)
            Shiny.setInputValue('show_rows',rowInfo)
            Shiny.setInputValue('show_details', 
            { index: rowInfo.index + 1, 
            rnd: Math.random() })
          }
        }"
    )

    #footer <- function(values) format(sum(values, na.rm = TRUE), big.mark = ",")

    output$mytable <- renderReactable({

      reactable(
        mtcars,
        compact = TRUE,
        defaultColDef = colDef(minWidth = 30,
                               footerStyle = "font-weight: bold",
                               style = function(value, index, name) {
         list(background = ifelse(
           index==
             input$show_details$index,
           "darksalmon",
           "white"),
         border='solid',
         borderWidth='1px 0px 0px 0px',
         margin = "0px")}

  ),
        highlight = TRUE,
        defaultPageSize = round((1200 - 345) / 31),
        paginationType = "simple",
        wrap = FALSE,
        onClick = onclick_js)
    })

    observeEvent(input$show_details,{
        print(input$show_details)})

    observeEvent(input$show_rows,{
        print(input$show_rows)
        })
}


# Run the application
shinyApp(ui = ui, server = server)