#' Create a submit button
#'
#' Create a submit button for an input form. Forms that include a submit
#' button do not automatically update their outputs when inputs change,
#' rather they wait until the user explicitly clicks the submit button.
#'
#' @param text Button caption
#' @param icon Optional \code{\link{icon}} to appear on the button
#' @param width The width of the button, e.g. \code{'400px'}, or \code{'100\%'};
#'   see \code{\link{validateCssUnit}}.
#' @return A submit button that can be added to a UI definition.
#'
#' @family input elements
#'
#' @examples
#' submitButton("Update View")
#' submitButton("Update View", icon("refresh"))
#' @export
submitButton <- function(text = "Apply Changes", icon = NULL, width = NULL) {
  div(
    tags$button(
      type="submit",
      class="btn btn-primary",
      style = if (!is.null(width)) paste0("width: ", validateCssUnit(width), ";"),
      list(icon, text)
    )
  )
}