feat(sec.js): support style attribute

Adds support for new style attribute on sectioning
elements, mapping to data-ams-style.
- readme/docs:
  - update attribute mappings
- sec.js
  - map style to data-ams-style (matching statement)
- test
  - add test case and test

Resolves #461

README.md

@@ -132,7 +132,7 @@ Beyond HTML element and attributes, texml-to-html stores data in custom `data-*`
   - underline
   - {disp-quote@specific-use}
   - (inline-)graphic{@specific-use}
-  - {@style} [expected: theorem styles]
+  - {@style} [expected: theorem styles, sec styles]
   - boxed (from boxed-text)
 - data-ams-ref
   - {@ref-type} [expected: bibr, fn, disp-formula, sec, fig, table, algorithm, list, statement]
@@ -250,7 +250,7 @@ The following provide a list from the reverse point of view.
 - attributes
   - @disp-level => data-ams-doc-level [data-ams-doc-level is also added to some elements that lack disp-level]
   - @content-type => data-ams-content-type
-  - @style => data-ams-style
+  - @style => data-ams-style [e.g., statement, sec]
   - @specific-use => data-ams-specific-use [sometimes mapped to other attributes, e.g., style]
   - @has-qed-box => data-ams-qed-box
   - @position => data-ams-position

lib/elements/sec.js

@@ -53,6 +53,8 @@ export default function (htmlParentNode, xmlnode) {
   });
   htmlParentNode.appendChild(section);
 
+  if (xmlnode.hasAttribute('style')) section.setAttribute('data-ams-style', xmlnode.getAttribute('style')); 
+
   if (specificUse === 'part') {
     section.setAttribute('role', 'doc-part');
   }

test/book.xml

@@ -209,6 +209,9 @@
                         <sec id="inpartlabel" disp-level="3"  specific-use="section">
                         <label>Label</label>
                         </sec>
+                        <sec id="xcb" disp-level="3"  specific-use="section" style="xcb">
+                        <label>Exercise</label>
+                        </sec>
                     </sec>
                 </sec>
 

test/element-sec-app-front-matter-part-dedication-title-label.js

@@ -19,7 +19,7 @@ import tape from 'tape';
 
 
 tape('sec, app, front-matter-part, dedication, title, label', async function (t) {
-  t.plan(43);
+  t.plan(44);
   const document = article;
 
   t.ok(document.querySelector('#ack1[role="doc-acknowledgments"][data-ams-doc-level="1"]'), 'ack to role doc-acknowledgments with data-ams-doc-level');
@@ -65,6 +65,7 @@ tape('sec, app, front-matter-part, dedication, title, label', async function (t)
   t.equal(document2.querySelector('#part').getAttribute('role'), 'doc-part', 'part role');
   t.ok(document2.querySelector('#inparttitle h2'), 'sec with title in chapter in part: heading level reduced');
   t.ok(document2.querySelector('#inpartlabel h2'), 'sec with label in chapter in part: heading level reduced');
+  t.equal(document2.querySelector('#xcb').getAttribute('data-ams-style'), 'xcb', 'sec with style, mapped to data-ams-style');
 
   t.ok(document2.querySelector('#fmtitle header p[data-ams-doc="subtitle"]'), 'sec with title: subtitle to p with data-ams-doc');
   t.ok(document2.querySelector('#fmlabel header p[data-ams-doc="subtitle"]'), 'sec with title: subtitle to p with data-ams-doc');