From e90f7afc607a0af326c87ebb184b7eacfee8b92b Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Wed, 14 Mar 2012 10:10:56 -0400
Subject: New JavaScript FFI function: setInnerHTML

---
 doc/manual.tex | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'doc/manual.tex')

diff --git a/doc/manual.tex b/doc/manual.tex
index 45c5479f..c18a594c 100644
--- a/doc/manual.tex
+++ b/doc/manual.tex
@@ -2384,6 +2384,8 @@ It is possible to write JavaScript FFI code that interacts with the functional-r
 
 \item The behavior of the \cd{<dyn>} pseudo-tag may be mimicked by following the right convention in a piece of HTML source code with a type like $\mt{xbody}$.  Such a piece of source code may be encoded with a JavaScript string.  To insert a dynamic section, include a \cd{<script>} tag whose content is just a call \cd{dyn(pnode, s)}.  The argument \cd{pnode} specifies what the relevant enclosing parent tag is.  Use value \cd{"tr"} when the immediate parent is \cd{<tr>}, use \cd{"table"} when the immediate parent is \cd{<table>}, and use \cd{"span"} otherwise.  The argument \cd{s} is a string-valued signal giving the HTML code to be inserted at this point.  As with the usual \cd{<dyn>} tag, that HTML subtree is automatically updated as the value of \cd{s} changes.
 
+\item There is only one supported method of taking HTML values generated in Ur/Web code and adding them to the DOM in FFI JavaScript code: call \cd{setInnerHTML(node, html)} to add HTML content \cd{html} within DOM node \cd{node}.  Merely running \cd{node.innerHTML = html} is not guaranteed to get the job done, though programmers familiar with JavaScript will probably find it useful to think of \cd{setInnerHTML} as having this effect.  The unusual idiom is required because Ur/Web uses a nonstandard representation of HTML, to support infinite nesting of code that may generate code that may generate code that....  The \cd{node} value must already be in the DOM tree at the point when \cd{setInnerHTML} is called, because some plumbing must be set up to interact sensibly with \cd{<dyn>} tags. 
+
 \item It is possible to use the more standard ``IDs and mutation'' style of JavaScript coding, though that style is unidiomatic for Ur/Web and should be avoided wherever possible.  Recall the abstract type $\mt{id}$ and its constructor $\mt{fresh}$, which can be used to generate new unique IDs in Ur/Web code.  Values of this type are represented as strings in JavaScript, and a function \cd{fresh()} is available to generate new unique IDs.  Application-specific ID generation schemes may cause bad interactions with Ur/Web code that also generates IDs, so the recommended approach is to produce IDs only via calls to \cd{fresh()}.  FFI code shouldn't depend on the ID generation scheme (on either server side or client side), but it is safe to include these IDs in tag attributes (in either server-side or client-side code) and manipulate the associated DOM nodes in the standard way (in client-side code).  Be forewarned that this kind of imperative DOM manipulation may confuse the Ur/Web runtime system and interfere with proper behavior of tags like \cd{<dyn>}!
 \end{itemize}
 
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