feat: add slugify option, improve example in README, add correspond…

…ing test

README.md

@@ -194,9 +194,9 @@ documents on the same page.
 Allows you to customize the slug function that create ids from string.
 
 Ex:
-```jsx
+```js
    // ...
-   slugify : string => `/some/prefix/${uslug(string).replace(/\//g, '_')}`
+   slugify : string => `/some/prefix/${string.replace(/(\/| |')/g, "_")}`
    // ...
 ```
 

src/__tests__/anchor.js

@@ -88,4 +88,18 @@ test("markdown-it-toc-and-anchor anchor", t => {
     "should handle not including default class" +
       " in anchors when setting anchorClassName to null"
   );
+
+  t.is(
+    mdIt(
+      `@[toc]
+# test me i'm famous`,
+      {
+        slugify: string => `/some/prefix/${string.replace(/(\/| |')/g, "_")}`
+      }
+    ),
+    `<p></p>
+<h1 id="/some/prefix/test_me_i_m_famous">test me i'm famous</h1>
+`,
+    "should support custom slugify function from readme"
+  );
 });

src/index.js

@@ -11,8 +11,8 @@ let tocHtml = "";
 
 const repeat = (string, num) => new Array(num + 1).join(string);
 
-const makeSafe = (string, headingIds) => {
-  const key = uslug(string); // slugify
+const makeSafe = (string, headingIds, slugifyFn) => {
+  const key = slugifyFn(string); // slugify
   if (!headingIds[key]) {
     headingIds[key] = 0;
   }
@@ -167,6 +167,9 @@ export default function(md, options) {
     let tocMarkdown = "";
     let tocTokens = [];
 
+    const slugifyFn =
+      (typeof options.slugify === "function" && options.slugify) || uslug;
+
     for (let i = 0; i < tokens.length; i++) {
       if (tokens[i].type !== "heading_close") {
         continue;
@@ -185,12 +188,13 @@ export default function(md, options) {
           // headings that contain links have to be processed
           // differently since nested links aren't allowed in markdown
           content = heading.children[1].content;
-          heading._tocAnchor = makeSafe(content, headingIds);
+          heading._tocAnchor = makeSafe(content, headingIds, slugifyFn);
         } else {
           content = heading.content;
           heading._tocAnchor = makeSafe(
             heading.children.reduce((acc, t) => acc + t.content, ""),
-            headingIds
+            headingIds,
+            slugifyFn
           );
         }