feat: add altText as a data attribute to rendered span

Author: drizco

src/expandableImages.js

@@ -19,18 +19,20 @@ module.exports = function expandableImages() {
       link.alt &&
       link.alt.endsWith("expandable")
     ) {
+      const altText = link.alt.replace(/expandable$/, "").trim()
       link.type = "span";
       link.data = {
         hName: "span",
         hProperties: {
           dataUrl: link.url,
+          dataAlt: altText,
           className: "expandable-image"
         }
       };
       link.children = [
         {
           type: "text",
-          value: link.alt.substr(0, -1 * "expandable".length).trim()
+          value: altText
         }
       ];
     }

test/utils.js

@@ -21,7 +21,7 @@ schema.attributes.img.push('height', 'width');
 
 // Add support for expandableImages
 schema.tagNames.push('span');
-schema.attributes.span = ['dataUrl', 'className'];
+schema.attributes.span = ['dataUrl', 'dataAlt', 'className'];
 
 // Add support for inline styles (gross)
 // TODO replace all inline styles in our curriculum content with