feat: Replace client-side markdown rendering with server-side in showcase mode (#4306)

* feat: Replace client-side markdown rendering with server-side in showcase mode

* `devtools::document()` (GitHub Actions)

* chore: callout rendering differences may happen

DESCRIPTION

@@ -60,10 +60,6 @@ Authors@R: c(
            comment = "Javascript strftime library"),
     person(, "SpryMedia Limited", role = c("ctb", "cph"),
            comment = "DataTables library"),
-    person("John", "Fraser", role = c("ctb", "cph"),
-           comment = "showdown.js library"),
-    person("John", "Gruber", role = c("ctb", "cph"),
-           comment = "showdown.js library"),
     person("Ivan", "Sagalaev", role = c("ctb", "cph"),
            comment = "highlight.js library"),
     person("R Core Team", role = c("ctb", "cph"),
@@ -83,7 +79,7 @@ Imports:
     bslib (>= 0.6.0),
     cachem (>= 1.1.0),
     cli,
-    commonmark (>= 1.7),
+    commonmark (>= 2.0.0),
     fastmap (>= 1.1.1),
     fontawesome (>= 0.4.0),
     glue (>= 1.3.2),

NEWS.md

@@ -42,6 +42,8 @@
 
 ## Changes
 
+* Markdown rendering in showcase mode now uses server-side rendering with the `{commonmark}` package, providing support for GitHub Flavored Markdown features (tables, strikethrough, autolinks, task lists). While most existing README.md files should continue to work as expected, some minor rendering differences may occur due to the change in markdown processor. (#4202, #4201)
+
 * The return value of `actionButton()`/`actionLink()` changed slightly: `label` and `icon` are wrapped in an additional HTML container element. This allows for: 1. `updateActionButton()`/`updateActionLink()` to distinguish between the `label` and `icon` when making updates and 2. spacing between `label` and `icon` to be more easily customized via CSS.
 
 # shiny 1.11.1

R/showcase.R

@@ -33,13 +33,6 @@ showcaseHead <- function() {
 
   deps  <- list(
     jqueryuiDependency(),
-    htmlDependency(
-      "showdown",
-      "0.3.1",
-      src = "www/shared/showdown/compressed",
-      package="shiny",
-      script = "showdown.js"
-    ),
     htmlDependency(
       "highlight.js",
       "6.2",
@@ -61,10 +54,11 @@ showcaseHead <- function() {
 
   mdfile <- file.path.ci(getwd(), 'Readme.md')
   html <- tagList(
-    if (file.exists(mdfile))
-      tags$script(type="text/markdown", id="showcase-markdown-content",
-        paste(readUTF8(mdfile), collapse="\n"))
-    else ""
+    if (file.exists(mdfile)) {
+      md_content <- paste(readUTF8(mdfile), collapse="\n")
+      md_html <- commonmark::markdown_html(md_content, extensions = TRUE)
+      tags$template(id="showcase-markdown-content", HTML(md_html))
+    } else ""
   )
 
   return(attachDependencies(html, deps))

inst/www/shared/shiny-showcase.js

@@ -1,3 +1,3 @@
 /*! shiny 1.11.1.9001 | (c) 2012-2025 Posit Software, PBC. | License: GPL-3 | file LICENSE */
-"use strict";(()=>{var m=400;function c(e,l){let t=0;if(e.nodeType===3){let n=e.nodeValue?.replace(/\n/g,"").length??0;if(n>=l)return{element:e,offset:l};t+=n}else if(e.nodeType===1&&e.firstChild){let n=c(e.firstChild,l);if(n.element!==null)return n;t+=n.offset}return e.nextSibling?c(e.nextSibling,l-t):{element:null,offset:t}}function r(e,l,t){let n=0;for(let s=0;s<e.childNodes.length;s++){let i=e.childNodes[s];if(i.nodeType===3){let o=/\n/g,d;for(;(d=o.exec(i.nodeValue))!==null;)if(n++,n===l)return c(i,d.index+t+1)}else if(i.nodeType===1){let o=r(i,l-n,t);if(o.element!==null)return o;n+=o.offset}}return{element:null,offset:n}}function p(e,l){if(!document.createRange)return;let t=document.getElementById("srcref_"+e);if(!t){t=document.createElement("span"),t.id="srcref_"+e;let n=e,s=document.getElementById(l.replace(/\./g,"_")+"_code");if(!s)return;let i=r(s,n[0],n[4]),o=r(s,n[2],n[5]);if(i.element===null||o.element===null)return;let d=document.createRange();i.element.parentNode?.nodeName==="SPAN"&&i.element!==o.element?d.setStartBefore(i.element.parentNode):d.setStart(i.element,i.offset),o.element.parentNode?.nodeName==="SPAN"&&i.element!==o.element?d.setEndAfter(o.element.parentNode):d.setEnd(o.element,o.offset),d.surroundContents(t)}$(t).stop(!0,!0).effect("highlight",null,1600)}window.Shiny&&window.Shiny.addCustomMessageHandler("showcase-src",function(e){e.srcref&&e.srcfile&&p(e.srcref,e.srcfile)});var a=!1,u=function(e,l){let t=l?m:1,n=e?document.getElementById("showcase-sxs-code"):document.getElementById("showcase-code-inline"),s=e?document.getElementById("showcase-code-inline"):document.getElementById("showcase-sxs-code");if(document.getElementById("showcase-app-metadata")===null){let o=$("#showcase-well");e?o.fadeOut(t):o.fadeIn(t)}if(n===null||s===null){console.warn("Could not find the host elements for the code tabs. This is likely a bug in the showcase app.");return}$(n).hide(),$(s).fadeOut(t,function(){let o=document.getElementById("showcase-code-tabs");if(o===null){console.warn("Could not find the code tabs element. This is likely a bug in the showcase app.");return}if(s.removeChild(o),n.appendChild(o),e?w():document.getElementById("showcase-code-content")?.removeAttribute("style"),$(n).fadeIn(t),!e&&(document.getElementById("showcase-app-container")?.removeAttribute("style"),l)){let f=$(n).offset()?.top;f!==void 0&&$(document.body).animate({scrollTop:f})}let d=document.getElementById("readme-md");d!==null&&(d.parentElement?.removeChild(d),e?(s.appendChild(d),$(s).fadeIn(t)):document.getElementById("showcase-app-metadata")?.appendChild(d)),document.getElementById("showcase-code-position-toggle").innerHTML=e?'<i class="fa fa-level-down"></i> show below':'<i class="fa fa-level-up"></i> show with app'}),e&&$(document.body).animate({scrollTop:0},t),a=e,h(e&&l),$(window).trigger("resize")};function h(e){let t=960,n=1,s=document.getElementById("showcase-app-code").offsetWidth;s/2>960?t=s/2:s*.66>960?t=960:(t=s*.66,n=t/960),$("#showcase-app-container").animate({width:t+"px",zoom:n*100+"%"},e?m:0)}var g=function(){u(!a,!0)},y=function(){document.body.offsetWidth>1350&&u(!0,!1)};function w(){document.getElementById("showcase-code-content").style.height=$(window).height()+"px"}function E(){let e=document.getElementById("showcase-markdown-content");if(e!==null){let l=e.innerText||e.innerHTML,t=window.Showdown.converter;document.getElementById("readme-md").innerHTML=new t().makeHtml(l)}}$(window).resize(function(){a&&(h(!1),w())});window.toggleCodePosition=g;$(window).on("load",y);$(window).on("load",E);window.hljs&&window.hljs.initHighlightingOnLoad();})();
+"use strict";(()=>{var m=400;function c(e,s){let t=0;if(e.nodeType===3){let n=e.nodeValue?.replace(/\n/g,"").length??0;if(n>=s)return{element:e,offset:s};t+=n}else if(e.nodeType===1&&e.firstChild){let n=c(e.firstChild,s);if(n.element!==null)return n;t+=n.offset}return e.nextSibling?c(e.nextSibling,s-t):{element:null,offset:t}}function a(e,s,t){let n=0;for(let l=0;l<e.childNodes.length;l++){let i=e.childNodes[l];if(i.nodeType===3){let o=/\n/g,d;for(;(d=o.exec(i.nodeValue))!==null;)if(n++,n===s)return c(i,d.index+t+1)}else if(i.nodeType===1){let o=a(i,s-n,t);if(o.element!==null)return o;n+=o.offset}}return{element:null,offset:n}}function g(e,s){if(!document.createRange)return;let t=document.getElementById("srcref_"+e);if(!t){t=document.createElement("span"),t.id="srcref_"+e;let n=e,l=document.getElementById(s.replace(/\./g,"_")+"_code");if(!l)return;let i=a(l,n[0],n[4]),o=a(l,n[2],n[5]);if(i.element===null||o.element===null)return;let d=document.createRange();i.element.parentNode?.nodeName==="SPAN"&&i.element!==o.element?d.setStartBefore(i.element.parentNode):d.setStart(i.element,i.offset),o.element.parentNode?.nodeName==="SPAN"&&i.element!==o.element?d.setEndAfter(o.element.parentNode):d.setEnd(o.element,o.offset),d.surroundContents(t)}$(t).stop(!0,!0).effect("highlight",null,1600)}window.Shiny&&window.Shiny.addCustomMessageHandler("showcase-src",function(e){e.srcref&&e.srcfile&&g(e.srcref,e.srcfile)});var r=!1,u=function(e,s){let t=s?m:1,n=e?document.getElementById("showcase-sxs-code"):document.getElementById("showcase-code-inline"),l=e?document.getElementById("showcase-code-inline"):document.getElementById("showcase-sxs-code");if(document.getElementById("showcase-app-metadata")===null){let o=$("#showcase-well");e?o.fadeOut(t):o.fadeIn(t)}if(n===null||l===null){console.warn("Could not find the host elements for the code tabs. This is likely a bug in the showcase app.");return}$(n).hide(),$(l).fadeOut(t,function(){let o=document.getElementById("showcase-code-tabs");if(o===null){console.warn("Could not find the code tabs element. This is likely a bug in the showcase app.");return}if(l.removeChild(o),n.appendChild(o),e?p():document.getElementById("showcase-code-content")?.removeAttribute("style"),$(n).fadeIn(t),!e&&(document.getElementById("showcase-app-container")?.removeAttribute("style"),s)){let f=$(n).offset()?.top;f!==void 0&&$(document.body).animate({scrollTop:f})}let d=document.getElementById("readme-md");d!==null&&(d.parentElement?.removeChild(d),e?(l.appendChild(d),$(l).fadeIn(t)):document.getElementById("showcase-app-metadata")?.appendChild(d)),document.getElementById("showcase-code-position-toggle").innerHTML=e?'<i class="fa fa-level-down"></i> show below':'<i class="fa fa-level-up"></i> show with app'}),e&&$(document.body).animate({scrollTop:0},t),r=e,h(e&&s),$(window).trigger("resize")};function h(e){let t=960,n=1,l=document.getElementById("showcase-app-code").offsetWidth;l/2>960?t=l/2:l*.66>960?t=960:(t=l*.66,n=t/960),$("#showcase-app-container").animate({width:t+"px",zoom:n*100+"%"},e?m:0)}var w=function(){u(!r,!0)},y=function(){document.body.offsetWidth>1350&&u(!0,!1)};function p(){document.getElementById("showcase-code-content").style.height=$(window).height()+"px"}function E(){let e=document.getElementById("showcase-markdown-content");if(e!==null){let s=document.getElementById("readme-md");if(s!==null){let t=e.content.cloneNode(!0);s.appendChild(t)}}}$(window).resize(function(){r&&(h(!1),p())});window.toggleCodePosition=w;$(window).on("load",y);$(window).on("load",E);window.hljs&&window.hljs.initHighlightingOnLoad();})();
 //# sourceMappingURL=shiny-showcase.js.map

inst/www/shared/showdown/license.txt

@@ -1,34 +0,0 @@
-Copyright (c) 2007, John Fraser  
-<http://www.attacklab.net/>  
-All rights reserved.
-
-Original Markdown copyright (c) 2004, John Gruber  
-<http://daringfireball.net/>  
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are
-met:
-
-* Redistributions of source code must retain the above copyright notice,
-  this list of conditions and the following disclaimer.
-
-* Redistributions in binary form must reproduce the above copyright
-  notice, this list of conditions and the following disclaimer in the
-  documentation and/or other materials provided with the distribution.
-
-* Neither the name "Markdown" nor the names of its contributors may
-  be used to endorse or promote products derived from this software
-  without specific prior written permission.
-
-This software is provided by the copyright holders and contributors "as
-is" and any express or implied warranties, including, but not limited
-to, the implied warranties of merchantability and fitness for a
-particular purpose are disclaimed. In no event shall the copyright owner
-or contributors be liable for any direct, indirect, incidental, special,
-exemplary, or consequential damages (including, but not limited to,
-procurement of substitute goods or services; loss of use, data, or
-profits; or business interruption) however caused and on any theory of
-liability, whether in contract, strict liability, or tort (including
-negligence or otherwise) arising in any way out of the use of this
-software, even if advised of the possibility of such damage.

man/shiny-package.Rd

@@ -59,8 +59,6 @@ Other contributors:
   \item Denis Ineshin (ion.rangeSlider library) [contributor, copyright holder]
   \item Sami Samhuri (Javascript strftime library) [contributor, copyright holder]
   \item  SpryMedia Limited (DataTables library) [contributor, copyright holder]
-  \item John Fraser (showdown.js library) [contributor, copyright holder]
-  \item John Gruber (showdown.js library) [contributor, copyright holder]
   \item Ivan Sagalaev (highlight.js library) [contributor, copyright holder]
   \item R Core Team (tar implementation from R) [contributor, copyright holder]
 }

package-lock.json

@@ -1,12 +1,12 @@
 {
-  "name": "@types/rstudio-shiny",
-  "version": "1.11.1-alpha.9000",
+  "name": "@posit/shiny",
+  "version": "1.11.1-alpha.9001",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
-      "name": "@types/rstudio-shiny",
-      "version": "1.11.1-alpha.9000",
+      "name": "@posit/shiny",
+      "version": "1.11.1-alpha.9001",
       "license": "GPL-3.0-only",
       "dependencies": {
         "@types/bootstrap": "5.2.x",
@@ -23,7 +23,6 @@
         "@types/jqueryui": "1.12.24",
         "@types/lodash": "4.x",
         "@types/node": "18.x",
-        "@types/showdown": "1.x",
         "@typescript-eslint/eslint-plugin": "8.x",
         "@typescript-eslint/parser": "8.x",
         "autoprefixer": "10.x",
@@ -2421,13 +2420,6 @@
       "integrity": "sha512-ABnSEXM1MyO9ZZXl2yXLqzHcENuGh6kyXisnq87OQCubbJrMaargMYV/NPVmJA3lJGnDM6hzc1ce7yQM/RwI5g==",
       "license": "MIT"
     },
-    "node_modules/@types/showdown": {
-      "version": "1.9.4",
-      "resolved": "https://registry.npmjs.org/@types/showdown/-/showdown-1.9.4.tgz",
-      "integrity": "sha512-50ehC3IAijfkvoNqmQ+VL73S7orOxmAK8ljQAFBv8o7G66lAZyxQj1L3BAv2dD86myLXI+sgKP1kcxAaxW356w==",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/@types/sizzle": {
       "version": "2.3.9",
       "resolved": "https://registry.npmjs.org/@types/sizzle/-/sizzle-2.3.9.tgz",

package.json

@@ -33,7 +33,6 @@
     "@types/jqueryui": "1.12.24",
     "@types/lodash": "4.x",
     "@types/node": "18.x",
-    "@types/showdown": "1.x",
     "@typescript-eslint/eslint-plugin": "8.x",
     "@typescript-eslint/parser": "8.x",
     "autoprefixer": "10.x",

srcts/extras/shiny-showcase.ts

@@ -299,20 +299,18 @@ function setCodeHeightFromDocHeight() {
     $(window).height() + "px";
 }
 
-// if there's a block of markdown content, render it to HTML
-function renderMarkdown() {
-  const mdContent = document.getElementById("showcase-markdown-content");
+// Move server-rendered markdown from template into the readme container
+function insertMarkdownContent() {
+  const template = document.getElementById(
+    "showcase-markdown-content",
+  ) as HTMLTemplateElement | null;
 
-  if (mdContent !== null) {
-    // IE8 puts the content of <script> tags into innerHTML but
-    // not innerText
-    const content = mdContent.innerText || mdContent.innerHTML;
-
-    const showdownConverter = (window as any).Showdown
-      .converter as showdown.ConverterStatic;
-
-    document.getElementById("readme-md")!.innerHTML =
-      new showdownConverter().makeHtml(content);
+  if (template !== null) {
+    const readmeContainer = document.getElementById("readme-md");
+    if (readmeContainer !== null) {
+      const content = template.content.cloneNode(true);
+      readmeContainer.appendChild(content);
+    }
   }
 }
 
@@ -331,7 +329,7 @@ declare global {
 window.toggleCodePosition = toggleCodePosition;
 
 $(window).on("load", setInitialCodePosition);
-$(window).on("load", renderMarkdown);
+$(window).on("load", insertMarkdownContent);
 
 if (window.hljs) window.hljs.initHighlightingOnLoad();