# Register a small JavaScript snippet with the page

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

## Usage

``` r
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

``` r
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"
    )
  )
}
```