Register a small JavaScript snippet with the page

Adds one inline JavaScript snippet to the page and attaches the shiny.webawesome dependency.

Usage

wa_js(code)

Arguments

code

One non-missing JavaScript string to inject into the page.

Value

A <script> tag with the shiny.webawesome dependency attached.

Details

wa_js() is a small package-level helper for app-local browser glue that should remain easy to see from the surrounding Shiny code. Typical uses include listening for browser-side events, reading live component properties, and publishing values back to Shiny with Shiny.setInputValue().

A typical property-read pattern is:

1. find the browser element by DOM id

2. read the live property in JavaScript

3. publish the value with Shiny.setInputValue()

4. consume the published value in Shiny as an ordinary input

This helper is intentionally narrow. It accepts a scalar JavaScript string and injects it into the rendered page. For larger or shared scripts, prefer standard Shiny asset patterns such as www/ files and tags$script().

Examples

if (interactive()) {
  ui <- webawesomePage(
    wa_js("
      function publishDetailsOpen() {
        const details = document.getElementById('details');

        if (!details ||
            !window.Shiny ||
            typeof window.Shiny.setInputValue !== 'function') {
          return;
        }

        window.Shiny.setInputValue(
          'details_open_state',
          details.open,
          { priority: 'event' }
        );
      }

      document.addEventListener('shiny:connected', publishDetailsOpen, {
        once: true
      });

      document.addEventListener('wa-show', function(event) {
        if (event.target.id === 'details') {
          publishDetailsOpen();
        }
      });

      document.addEventListener('wa-hide', function(event) {
        if (event.target.id === 'details') {
          publishDetailsOpen();
        }
      });
    "),
    wa_details(
      input_id = "details",
      summary = "More information",
      "Details body"
    ),
    shiny::verbatimTextOutput("details_state")
  )

  server <- function(input, output, session) {
    output$details_state <- shiny::renderPrint({
      input$details_open_state
    })
  }

  shiny::shinyApp(ui, server)
}

if (interactive()) {
  js_file <- tempfile(fileext = ".js")
  writeLines(
    c(
      "document.addEventListener('wa-show', function(event) {",
      "  if (event.target.id !== 'details') {",
      "    return;",
      "  }",
      "",
      "  if (window.Shiny &&",
      "      typeof window.Shiny.setInputValue === 'function') {",
      "    window.Shiny.setInputValue(",
      "      'details_open_state',",
      "      event.target.open,",
      "      { priority: 'event' }",
      "    );",
      "  }",
      "});"
    ),
    js_file
  )

  js_code <- paste(readLines(js_file, warn = FALSE), collapse = "\n")

  ui <- webawesomePage(
    wa_js(js_code),
    wa_details(
      input_id = "details",
      summary = "More information",
      "Details body"
    )
  )
}