FR: extract HTML text from tags

[ismirsehregal]

Coming from here.

I'm wondering whether there is a way to extract the HTML text ("mylabel" in the example below) from a tag via {htmltools}.

Currently the following

library(htmltools)
library(shiny)

tagQuery(actionButton(
  inputId = "myid",
  label = "mylabel",
  icon = icon("home")
))$children()

results in:

`$allTags()`:
<button id="myid" type="button" class="btn btn-default action-button">
  <i class="fas fa-house" role="presentation" aria-label="house icon"></i>
  <span class="shiny-icon-separator"></span>
  mylabel
</button>

Error in (function (el, i)  : 
  `setSelected(selected=)` received a list item at position `3` that was not a tag environment

Related:

https://rvest.tidyverse.org/reference/html_text.html

[nteetor]

If tagQuery() is failing, perhaps the $children component of a tag object could be of use.

library(htmltools)

str(div())
#> List of 3
#>  $ name    : chr "div"
#>  $ attribs : Named list()
#>  $ children: list()
#>  - attr(*, "class")= chr "shiny.tag"

^{Created on 2025-07-01 with reprex v2.1.1}

As you highlight above, action buttons seem to cause problems for tagQuery()$children(). So, alternatively, here is a small function specifically to extract the label text from an action button.

library(htmltools)
library(shiny)

getActionButtonText <- 
  function(button) {
    button$children[[1]][[2]]
  }

buttonWithIcon <- 
  actionButton(
    inputId = "demo",
    label = "A demo button",
    icon = icon("home")
  )

getActionButtonText(buttonWithIcon)
#> [1] "A demo button"

buttonNoIcon <- 
  actionButton(
    inputId = "noIcon",
    label = "A button without an icon"
  )
    
getActionButtonText(buttonNoIcon)
#> [1] "A button without an icon"


buttonNoLabel <- 
  actionButton(
    inputId = "noLabel",
    label = NULL
  )

getActionButtonText(buttonNoLabel)
#> NULL

^{Created on 2025-07-01 with reprex v2.1.1}

[ismirsehregal]

@nteetor thanks for your response! Unfortunately, explicitly indexing the child elements is exactly what I am trying to get rid of (please see this issue).

[gadenbuie]

Here's a small example that uses tagQuery() to get the action button markup back to what it used to be:

library(htmltools)
library(shiny)

button <- actionButton(
  inputId = "myid",
  label = "mylabel",
  icon = icon("home")
)

tq <- tagQuery(tags$div(button))
sep <- tq$find(".shiny-icon-separator")
sep$remove()
#> `$allTags()`:
#> <div>
#>   <button id="myid" type="button" class="btn btn-default action-button">
#>     <i class="fas fa-house" role="presentation" aria-label="house icon"></i>
#>     mylabel
#>   </button>
#> </div>
#> 
#> `$selectedTags()`: (Empty selection)
tq$find(".action-button")$selectedTags() |> format()
#> [1] "<button id=\"myid\" type=\"button\" class=\"btn btn-default action-button\">\n  <i class=\"fas fa-house\" role=\"presentation\" aria-label=\"house icon\"></i>\n  mylabel\n</button>"

That said, indexing the children of actionButton() to find the icon and label is not a great idea. It'd be much better to take arguments or data from an outer function and call actionButton() on those arguments than to poke around in the markup.

Another option would be to use tags$button(class = "action-button", ...) with your own internal markup. Shiny creates button/link inputs for button.action-button or a.action-button elements, so that's the minimal markup required to create an action input.

As a last note, I strongly discourage indexing into Shiny's components because we do change internal markup from time to time to support new features or fix bugs.