Add attrReplace

A function to replace attr value for plugins.

lib/token.js

@@ -146,4 +146,38 @@ Token.prototype.attrPush = function attrPush(attrData) {
 };
 
 
+/**
+ * Token.attrReplace(name, value)
+ *
+ * Replace all attributes with name `name` with one with the value `attrData`
+ **/
+Token.prototype.attrReplace = function attrReplace(name, value) {
+  var found;
+
+  var attrs = this.attrs;
+
+  if (attrs) {
+    // modify the existing attr is possible
+    for (var i = 0; i < attrs.length; i++) {
+      if (attrs[i][0] === name) {
+        if (!found) {
+          attrs[i][1] = value;
+          found = true;
+        } else {
+          // remove extra attrs with same name
+          attrs.splice(i, 1);
+          i--;
+        }
+      }
+    }
+
+    // add a new attribute with such name if none was found
+    if (!found) {
+      attrs.push([name, value]);
+    }
+  } else {
+    this.attrs = [ [name, value] ];
+  }
+};
+
 module.exports = Token;