Coerce null/undefined to empty string when escaping

lib/ejs.rb

@@ -69,7 +69,7 @@ def js_unescape!(source)
 
       def replace_escape_tags!(source, options)
         source.gsub!(options[:escape_pattern] || escape_pattern) do
-          "',(''+#{js_unescape!($1)})#{escape_function},'"
+          "',#{coerce_to_string_function}(#{js_unescape!($1)})#{escape_function},'"
         end
       end
 
@@ -85,6 +85,12 @@ def replace_interpolation_tags!(source, options)
         end
       end
 
+      def coerce_to_string_function
+        "function(s) {" +
+          "return (s === null || typeof(s) === 'undefined') ? '' : ('' + s);" +
+        "}"
+      end
+
       def escape_function
         ".replace(/&/g, '&')" +
         ".replace(/</g, '&lt;')" +

test/test_ejs.rb

@@ -168,6 +168,12 @@ class EJSEvaluationTest < Test::Unit::TestCase
 
     template = "<%- foobar %>"
     assert_equal "&#x27;Foo Bar&#x27;", EJS.evaluate(template, { :foobar => "'Foo Bar'" })
+
+    template = "<%- null %>"
+    assert_equal "", EJS.evaluate(template, {})
+
+    template = "<%- undefined %>"
+    assert_equal "", EJS.evaluate(template, {})
   end
 
   test "braced escaping" do
@@ -182,6 +188,12 @@ class EJSEvaluationTest < Test::Unit::TestCase
 
     template = "{{- foobar }}"
     assert_equal "&#x27;Foo Bar&#x27;", EJS.evaluate(template, { :foobar => "'Foo Bar'" }, BRACE_SYNTAX)
+
+    template = "{{- null }}"
+    assert_equal "", EJS.evaluate(template, {}, BRACE_SYNTAX)
+
+    template = "{{- undefined }}"
+    assert_equal "", EJS.evaluate(template, {}, BRACE_SYNTAX)
   end
 
   test "question-mark escaping" do
@@ -196,5 +208,11 @@ class EJSEvaluationTest < Test::Unit::TestCase
 
     template = "<?- foobar ?>"
     assert_equal "&#x27;Foo Bar&#x27;", EJS.evaluate(template, { :foobar => "'Foo Bar'" }, QUESTION_MARK_SYNTAX)
+
+    template = "<?- null ?>"
+    assert_equal "", EJS.evaluate(template, {}, QUESTION_MARK_SYNTAX)
+
+    template = "<?- undefined ?>"
+    assert_equal "", EJS.evaluate(template, {}, QUESTION_MARK_SYNTAX)
   end
 end