From f118d9861e049fbccdbace4a570f6a2f489555c5 Mon Sep 17 00:00:00 2001
From: Ivan Voischev <voischev@yandex-team.ru>
Date: Sun, 18 Aug 2019 16:52:01 +0300
Subject: [PATCH] perf: extra performance

---
 lib/index.js | 149 ++++++++++++++++++++++++++++++---------------------
 1 file changed, 87 insertions(+), 62 deletions(-)

diff --git a/lib/index.js b/lib/index.js
index 46903cd..308e2c5 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -45,15 +45,60 @@ function render (tree, options) {
    */
   options = options || {}
 
-  var singleTags = SINGLE_TAGS.concat(options.singleTags || [])
+  var singleTags = options.singleTags ? SINGLE_TAGS.concat(options.singleTags) : SINGLE_TAGS
   var singleRegExp = singleTags.filter(function (tag) {
-    return tag instanceof RegExp ? tag : false
+    return tag instanceof RegExp
   })
 
   var closingSingleTag = options.closingSingleTag
 
   return html(tree)
 
+  /** @private */
+  function isSingleTag (tag) {
+    if (singleRegExp.length !== 0) {
+      for (var i = 0; i < singleRegExp.length; i++) {
+        return singleRegExp[i].test(tag)
+      }
+    }
+
+    if (singleTags.indexOf(tag) === -1) {
+      return false
+    }
+
+    return true
+  }
+
+  /** @private */
+  function attrs (obj) {
+    var attr = ''
+
+    for (var key in obj) {
+      if (typeof obj[key] === 'string') {
+        attr += ' ' + key + '="' + obj[key].replace(/"/g, '&quot;') + '"'
+      } else if (obj[key] === true) {
+        attr += ' ' + key
+      } else if (typeof obj[key] === 'number') {
+        attr += ' ' + key + '="' + obj[key] + '"'
+      }
+    }
+
+    return attr
+  }
+
+  /** @private */
+  function traverse (tree, cb) {
+    if (Array.isArray(tree)) {
+      for (var i = 0, length = tree.length; i < length; i++) {
+        traverse(cb(tree[i]), cb)
+      }
+    } else if (typeof tree === 'object' && tree.hasOwnProperty('content')) {
+      traverse(tree.content, cb)
+    }
+
+    return tree
+  }
+
   /**
    * HTML Stringifier
    *
@@ -64,21 +109,17 @@ function render (tree, options) {
   function html (tree) {
     var result = ''
 
-    traverse([].concat(tree), function (node) {
-      if (!node) return
-
-      if (typeof node === 'string' || typeof node === 'number') {
-        result += node
+    tree = Array.isArray(tree) ? tree : [tree]
 
+    traverse(tree, function (node) {
+      // undefined, null, '', [], NaN
+      if (node === undefined ||
+          node === null ||
+          node.length === 0 ||
+          Number.isNaN(node)) {
         return
       }
 
-      if (typeof node.tag === 'boolean' && !node.tag) {
-        typeof node.content !== 'object' && (result += node.content)
-
-        return node.content
-      }
-
       // treat as new root tree if node is an array
       if (Array.isArray(node)) {
         result += html(node)
@@ -86,9 +127,24 @@ function render (tree, options) {
         return
       }
 
+      if (typeof node === 'string' || typeof node === 'number') {
+        result += node
+
+        return
+      }
+
+      // skip node
+      if (node.tag === false) {
+        if (typeof node.content === 'string' || typeof node.content === 'number') {
+          result += node.content
+        }
+
+        return node.content
+      }
+
       var tag = node.tag || 'div'
 
-      if (isSingleTag(tag, singleTags, singleRegExp)) {
+      if (isSingleTag(tag)) {
         result += '<' + tag + attrs(node.attrs)
 
         switch (closingSingleTag) {
@@ -104,9 +160,23 @@ function render (tree, options) {
             result += '>'
         }
 
-        result += node.content ? html(node.content) : ''
+        if (node.hasOwnProperty('content')) {
+          return node.content
+        }
       } else {
-        result += '<' + tag + (node.attrs ? attrs(node.attrs) : '') + '>' + (node.content ? html(node.content) : '') + '</' + tag + '>'
+        result += '<' + tag
+
+        if (node.attrs) {
+          result += attrs(node.attrs)
+        }
+
+        result += '>'
+
+        if (node.hasOwnProperty('content')) {
+          result += html(node.content)
+        }
+
+        result += '</' + tag + '>'
       }
     })
 
@@ -117,52 +187,7 @@ function render (tree, options) {
 /**
  * @module posthtml-render
  *
- * @version 1.0.7
+ * @version 1.1.5
  * @license MIT
  */
 module.exports = render
-
-/** @private */
-function attrs (obj) {
-  var attr = ''
-
-  for (var key in obj) {
-    if (typeof obj[key] === 'boolean' && obj[key]) {
-      attr += ' ' + key
-    } else if (typeof obj[key] === 'number') {
-      attr += ' ' + key + '="' + obj[key] + '"'
-    } else if (typeof obj[key] === 'string') {
-      attr += ' ' + key + '="' + obj[key].replace(/"/g, '&quot;') + '"'
-    }
-  }
-
-  return attr
-}
-
-/** @private */
-function traverse (tree, cb) {
-  if (Array.isArray(tree)) {
-    for (var i = 0, length = tree.length; i < length; i++) {
-      traverse(cb(tree[i]), cb)
-    }
-  } else if (typeof tree === 'object' && tree.hasOwnProperty('content')) {
-    traverse(tree.content, cb)
-  }
-
-  return tree
-}
-
-/** @private */
-function isSingleTag (tag, singleTags, singleRegExp) {
-  if (singleRegExp.length) {
-    for (var i = 0; i < singleRegExp.length; i++) {
-      return !!tag.match(singleRegExp[i])
-    }
-  }
-
-  if (singleTags.indexOf(tag) === -1) {
-    return false
-  }
-
-  return true
-}