From 996f583d02e4a1cc2217ecf57771663401942f34 Mon Sep 17 00:00:00 2001
From: Postbot <postbot@users.noreply.github.com>
Date: Thu, 7 Sep 2017 18:29:32 +0800
Subject: [PATCH] Create
 _benchmarks/regex-without-lookahead-vs-regex-with-lookahead.md

---
 ...thout-lookahead-vs-regex-with-lookahead.md | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 _benchmarks/regex-without-lookahead-vs-regex-with-lookahead.md

diff --git a/_benchmarks/regex-without-lookahead-vs-regex-with-lookahead.md b/_benchmarks/regex-without-lookahead-vs-regex-with-lookahead.md
new file mode 100644
index 00000000..dd1cab9f
--- /dev/null
+++ b/_benchmarks/regex-without-lookahead-vs-regex-with-lookahead.md
@@ -0,0 +1,38 @@
+---
+title: Regex without lookahead vs Regex with lookahead
+setup: |
+  const attrs = [
+      'fa',
+      'has',
+      'is',
+      'fa-',
+      'has-',
+      'is-',
+      'fa-home',
+      'has-text-centered',
+      'is-primary',
+      'orientation',
+      'data-username',
+      'aria-hidden'
+    ]
+    
+    const checkAttribute = (attr, regex) => (new RegExp(regex)).test(attr)
+    const regexWithoutLookahead = '^(is|has|fa)-.+'
+    const regexWithLookahead = '^(?=(fa|has|is)-).+'
+tests:
+  -
+    name: Regex without lookahead
+    code: |
+      attrs.forEach(attr => {
+        const check = attr.trim().toLowerCase()
+        checkAttribute(check, regexWithoutLookahead)
+      })
+  -
+    name: Regex with lookahead
+    code: |
+      attrs.forEach(attr => {
+        const check = attr.trim().toLowerCase()
+        checkAttribute(check, regexWithLookahead)
+      })
+---
+