Implement the allowTags functionality

README.md

@@ -13,6 +13,18 @@ $ npm install strip
 ```js
 strip('<p> hello <a href="http://foo.com/?q=123">world</a> </p>');
 // => Hello World
+
+strip('<p>My name is <b>Jon</b>.</p>');
+// => Retrun "My name is Jon."
+
+strip('<p>My name is <b>Jon</b>.</p><p>I love <a href="en.wikipedia/wiki/dogs">dogs</a>.</p>');
+// => Retrun "My name is Jon. I love dogs."
+
+strip('<p>My name is <b>Jon</b>.</p><p>I love <a href="en.wikipedia/wiki/dogs">dogs</a>.</p>', 'a');
+// => "My name is Jon. I love <a href="en.wikipedia/wiki/dogs">dogs</a>."
+
+strip('<p>My name is <b>Jon</b>.</p><p>I love <a href="en.wikipedia/wiki/dogs">dogs</a>.</p>', 'a|b');
+// => "My name is <b>Jon</b>. I love <a href="en.wikipedia/wiki/dogs">dogs</a>."
 ```
 
 ![](https://dl.dropbox.com/s/9q2p5mrqnajys22/npmel.jpg?token_hash=AAHqttN9DiGl63ma8KRw-G0cdalaiMzrvrOPGnOfDslDjw)

index.js

@@ -1,5 +1,32 @@
 module.exports = strip;
 
-function strip(html){
-  return html.replace(/<[^<]+>/g, '').trim();
+/**
+ * Strip tags from html text.
+ * You can specify the allowed tag in format 'a', 'p|b' or 'b|i|p'
+ *
+ *
+ * @example
+ * var text = strip('<p>My name is <b>Jon</b>.</p>'); // Retrun "My name is Jon."
+ * var text = strip('<p>My name is <b>Jon</b>.</p><p>I love <a href="en.wikipedia/wiki/dogs">dogs</a>.</p>'); // Retrun "My name is Jon. I love dogs."
+ * var text = strip('<p>My name is <b>Jon</b>.</p><p>I love <a href="en.wikipedia/wiki/dogs">dogs</a>.</p>', 'a'); // Retrun "My name is Jon. I love <a href="en.wikipedia/wiki/dogs">dogs</a>."
+ * var text = strip('<p>My name is <b>Jon</b>.</p><p>I love <a href="en.wikipedia/wiki/dogs">dogs</a>.</p>', 'a|b'); // Retrun "My name is <b>Jon</b>. I love <a href="en.wikipedia/wiki/dogs">dogs</a>."
+ *
+ *
+ * @function
+ * @param  {String}  html       HTML string to stip tags
+ * @param  {String}  [allowed]  Allowed HTML tags
+ * @return  {String}
+ */
+
+function strip(html, allowed) {
+    // Normalize the allowed format. 'a|b|c' -> '|a|b|c|'
+    allowed = '|' + (allowed || '').toLowerCase() + '|';
+
+    if (allowed.length === 2) {
+        return html.replace(/<[^<]+>/g, '').trim();
+    } else {
+        return html.replace(/<\/?([a-z][a-z0-9]*)\b[^>]*>/gi, function(tag_body, tag_name) {
+            return (allowed.indexOf('|' + tag_name.toLowerCase() + '|') === -1) ? '' : tag_body;
+        }).trim();
+    }
 }