Conditional Styling

Source: vignettes/conditional-styling.Rmd

You can conditionally style a table using functions that return inline styles or CSS classes. Just like with custom rendering, style functions can either be in R or JavaScript:

R functions JavaScript functions 
reactable(
  iris,
  rowStyle = function(index) {
    if (iris[index, "Sepal.Width"] > 3.5) {
      list(fontWeight = "bold")
    }
  }
)
 
reactable(
  iris,
  rowStyle = JS("function(rowInfo) {
    if (rowInfo.row['Sepal.Width'] > 3.5) {
      return { fontWeight: 'bold' }
    }
  }")
)
  • Easier to use but more static
  • Style once, when the table is created
  • Harder to use but more dynamic
  • Style on the fly, based on client-side state

Whichever one to use depends on the situation and personal preference. You might prefer to use R functions except when you need more dynamic behavior (e.g., style based on sorted state).

Example: color scales

We can use R’s built-in color utilities to apply a color scale to a column:

data <- iris[1:5, ]
orange_pal <- function(x) rgb(colorRamp(c("#ffe4cc", "#ffb54d"))(x), maxColorValue = 255)

reactable(
  data,
  columns = list(
    Petal.Length = colDef(
      style = function(value) {
        normalized <- (value - min(data$Petal.Length)) / (max(data$Petal.Length) - min(data$Petal.Length))
        color <- orange_pal(normalized)
        list(background = color)
      }
    )
  )
)

Example: highlight sorted columns

To style sorted columns, we need to use a JavaScript function to determine whether a column is currently being sorted:

reactable(
  iris[1:5, ],
  defaultSorted = "Petal.Length",
  defaultColDef = colDef(
    class = JS("function(rowInfo, colInfo, state) {
      // Highlight sorted columns
      for (var i = 0; i < state.sorted.length; i++) {
        if (state.sorted[i].id === colInfo.id) {
          return 'sorted'
        }
      }
    }")
  )
)

Cell Styling

JavaScript functions

Or a JavaScript function, wrapped in JS(), with up to 3 optional arguments:

colDef(
  style = JS("
    function(rowInfo, colInfo, state) {
      // input:
      //  - rowInfo, an object containing row info
      //  - colInfo, an object containing column info (optional)
      //  - state, an object containing the table state (optional)
      //
      // output:
      //  - a style object with camelCased property names
      return { backgroundColor: 'gray' }
    }
  "),
  class = JS("
    function(rowInfo, colInfo, state) {
      // input:
      //  - rowInfo, an object containing row info
      //  - colInfo, an object containing column info (optional)
      //  - state, an object containing the table state (optional)
      //
      // output:
      //  - CSS class names
      return 'class1 class2'
    }
  ")
)

rowInfo properties

colInfo properties

state properties

Row Styling

R functions

Both rowStyle and rowClass take an R function with a single argument:

reactable(
  rowStyle = function(index) {
    # input:
    #   - index, the row index
    #
    # output:
    #   - a named list with camelCased property names
    list(color = "red", marginLeft = "30px")
    #   - or an inline style string
    "color: red; margin-left: 30px;"
  },
  rowClass = function(index) {
    # input:
    #   - index, the row index
    #
    # output:
    #   - CSS class names
    "class1 class2"
  }
)

NOTE: R functions cannot apply styles to aggregated rows.

JavaScript functions

Or a JavaScript function with up to 2 optional arguments:

reactable(
  rowStyle = JS("
    function(rowInfo, state) {
      // input:
      //  - rowInfo, an object containing row info
      //  - state, an object containing the table state (optional)
      //
      // output:
      //  - a style object with camelCased properties
      return { backgroundColor: 'gray' }
    }
  "),
  rowClass = JS("
    function(rowInfo, state) {
      // input:
      //  - rowInfo, an object containing row info
      //  - state, an object containing the table state (optional)
      //
      // output:
      //  - CSS class names
      return 'class1 class2'
    }
  ")
)

rowInfo properties

state properties