New .attrJoin() & .attrSet() methods in Token

lib/token.js

@@ -146,4 +146,38 @@ Token.prototype.attrPush = function attrPush(attrData) {
 };
 
 
+/**
+ * Token.attrSet(name, value)
+ *
+ * Set `name` attribute to `value`. Override old value if exists.
+ **/
+Token.prototype.attrSet = function attrSet(name, value) {
+  var idx = this.attrIndex(name),
+      attrData = [ name, value ];
+
+  if (idx < 0) {
+    this.attrPush(attrData);
+  } else {
+    this.attrs[idx] = attrData;
+  }
+};
+
+
+/**
+ * Token.attrJoin(name, value)
+ *
+ * Join value to existing attribute via space. Or create new attribute if not
+ * exists. Useful to operate with token classes.
+ **/
+Token.prototype.attrJoin = function attrJoin(name, value) {
+  var idx = this.attrIndex(name);
+
+  if (idx < 0) {
+    this.attrPush([ name, value ]);
+  } else {
+    this.attrs[idx][1] = this.attrs[idx][1] + ' ' + value;
+  }
+};
+
+
 module.exports = Token;

test/misc.js

@@ -303,3 +303,42 @@ describe('smartquotes', function () {
   });
 
 });
+
+
+describe('Token attributes', function () {
+  it('.attrJoin', function () {
+    var md = markdownit();
+
+    var tokens = md.parse('```'),
+        t = tokens[0];
+
+    t.attrJoin('class', 'foo');
+    t.attrJoin('class', 'bar');
+
+    assert.strictEqual(
+      md.renderer.render(tokens, md.options),
+      '<pre><code class="foo bar"></code></pre>\n'
+    );
+  });
+
+  it('.attrSet', function () {
+    var md = markdownit();
+
+    var tokens = md.parse('```'),
+        t = tokens[0];
+
+    t.attrSet('class', 'foo');
+
+    assert.strictEqual(
+      md.renderer.render(tokens, md.options),
+      '<pre><code class="foo"></code></pre>\n'
+    );
+
+    t.attrSet('class', 'bar');
+
+    assert.strictEqual(
+      md.renderer.render(tokens, md.options),
+      '<pre><code class="bar"></code></pre>\n'
+    );
+  });
+});