From 6d9bab7e9f24a53f268dcf69c7bc2d0a125f2be5 Mon Sep 17 00:00:00 2001
From: Titus Wormer <tituswormer@gmail.com>
Date: Sat, 17 Sep 2016 13:48:20 +0200
Subject: [PATCH] Allow empty string to supress prefix

Closes GH-4.
---
 lib/core.js   | 12 ++++++++++--
 test/index.js | 26 ++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/lib/core.js b/lib/core.js
index 226f277..dfc8974 100644
--- a/lib/core.js
+++ b/lib/core.js
@@ -78,7 +78,7 @@ var own = {}.hasOwnProperty;
  */
 function autoHighlight(value, options) {
   var settings = options || {};
-  var prefix = settings.prefix || DEFAULT_PREFIX;
+  var prefix = settings.prefix;
   var subset = settings.subset || languageNames;
   var length = subset.length;
   var index = -1;
@@ -87,6 +87,10 @@ function autoHighlight(value, options) {
   var current;
   var name;
 
+  if (prefix === null || prefix === undefined) {
+    prefix = DEFAULT_PREFIX;
+  }
+
   if (typeof value !== 'string') {
     throw new Error('Expected `string` for value, got `' + value + '`');
   }
@@ -134,7 +138,11 @@ function autoHighlight(value, options) {
 */
 function highlight(language, value, options) {
   var settings = options || {};
-  var prefix = settings.prefix || DEFAULT_PREFIX;
+  var prefix = settings.prefix;
+
+  if (prefix === null || prefix === undefined) {
+    prefix = DEFAULT_PREFIX;
+  }
 
   return normalize(coreHighlight(language, value, true, prefix));
 }
diff --git a/test/index.js b/test/index.js
index 3f488e4..f0046a4 100644
--- a/test/index.js
+++ b/test/index.js
@@ -173,6 +173,20 @@ test('lowlight.highlight(language, value[, options])', function (t) {
     st.end();
   });
 
+  t.test('empty `prefix`', function (st) {
+    var result = low.highlight('js', '"use strict";', {
+      prefix: ''
+    });
+
+    t.deepEqual(
+      result.value[0].properties.className,
+      ['meta'],
+      'should support an empty `prefix`'
+    );
+
+    st.end();
+  });
+
   t.end();
 });
 
@@ -269,6 +283,18 @@ test('lowlight(value[, options])', function (t) {
     st.end();
   });
 
+  t.test('empty `prefix`', function (st) {
+    var result = low.highlightAuto('"use strict";', {prefix: ''});
+
+    t.deepEqual(
+      result.value[0].properties.className,
+      ['meta'],
+      'should support an empty `prefix`'
+    );
+
+    st.end();
+  });
+
   t.test('custom `subset`', function (st) {
     var result = low.highlightAuto('"use strict";', {subset: ['java']});