Add option to overwrite the default prefilter for links

lib/configs/commonmark.js

@@ -12,6 +12,13 @@ module.exports = {
     linkify:      false,        // autoconvert URL-like texts to links
     linkTarget:   '',           // set target to open link in
 
+    // linkifyPrefilter. Function that overwrite the default link prefilter,
+    // specified by this regex: /www|@|\:\/\//
+    //
+    // @param { string } link that will be tested.
+    // @returns { Boolean } whether or not the link passes the prefilter.
+    linkifyPrefilter: null,
+
     // Enable some language-neutral replacements + quotes beautification
     typographer:  false,
 

lib/configs/default.js

@@ -12,6 +12,13 @@ module.exports = {
     linkify:      false,        // autoconvert URL-like texts to links
     linkTarget:   '',           // set target to open link in
 
+    // linkifyPrefilter. Function that overwrite the default link prefilter,
+    // specified by this regex: /www|@|\:\/\//
+    //
+    // @param { string } link that will be tested.
+    // @returns { Boolean } whether or not the link passes the prefilter.
+    linkifyPrefilter: null,
+
     // Enable some language-neutral replacements + quotes beautification
     typographer:  false,
 

lib/configs/full.js

@@ -12,6 +12,13 @@ module.exports = {
     linkify:      false,        // autoconvert URL-like texts to links
     linkTarget:   '',           // set target to open link in
 
+    // linkifyPrefilter. Function that overwrite the default link prefilter,
+    // specified by this regex: /www|@|\:\/\//
+    //
+    // @param { string } link that will be tested.
+    // @returns { Boolean } whether or not the link passes the prefilter.
+    linkifyPrefilter: null,
+
     // Enable some language-neutral replacements + quotes beautification
     typographer:  false,
 

lib/rules_core/linkify.js

@@ -95,7 +95,14 @@ module.exports = function linkify(state) {
       }
       if (htmlLinkLevel > 0) { continue; }
 
-      if (token.type === 'text' && LINK_SCAN_RE.test(token.content)) {
+      var linkifyPrefilter = state.options.linkifyPrefilter;
+      var passPrefilter = LINK_SCAN_RE.test(token.content);
+      if (linkifyPrefilter && typeof linkifyPrefilter === 'function') {
+        // Use the custom prefilter for links.
+        passPrefilter = linkifyPrefilter(token.content);
+      }
+
+      if (token.type === 'text' && passPrefilter) {
 
         // Init linkifier in lazy manner, only if required.
         if (!linkifier) {

test/misc.js

@@ -105,6 +105,20 @@ describe('API', function () {
     assert.strictEqual(md.render('```\n&\n```'), '<pre><code>&amp;\n</code></pre>\n');
   });
 
+  it('Linkify prefilter', function () {
+    var md = new Remarkable({
+      linkify: true,
+      linkifyPrefilter: function (str) {
+        // Only linkify if link starts with https://
+        return /^https?:\/\//.test(str);
+      }
+    });
+
+    assert.strictEqual(md.render('https://www.google.com'),
+      '<p><a href="https://www.google.com">https://www.google.com</a></p>\n');
+    assert.strictEqual(md.render('www.google.com'), '<p>www.google.com</p>\n');
+  });
+
   it('force hardbreaks', function () {
     var md = new Remarkable({ breaks: true });