LibJS: Handle empty values in Array.prototype.toString()

2 files changed, 8 insertions, 1 deletions

diff --git a/Libraries/LibJS/Runtime/ArrayPrototype.cpp b/Libraries/LibJS/Runtime/ArrayPrototype.cpp
index 8a295e96a3..56b007158c 100644
--- a/Libraries/LibJS/Runtime/ArrayPrototype.cpp
+++ b/Libraries/LibJS/Runtime/ArrayPrototype.cpp
@@ -100,7 +100,8 @@ Value ArrayPrototype::to_string(Interpreter& interpreter)
     for (size_t i = 0; i < array->elements().size(); ++i) {
         if (i != 0)
             builder.append(',');
-        builder.append(array->elements()[i].to_string());
+        if (!array->elements()[i].is_empty())
+            builder.append(array->elements()[i].to_string());
     }
     return js_string(interpreter, builder.to_string());
 }
diff --git a/Libraries/LibJS/Tests/Array.prototype.toString.js b/Libraries/LibJS/Tests/Array.prototype.toString.js
index 7b33f21183..afffee48ad 100644
--- a/Libraries/LibJS/Tests/Array.prototype.toString.js
+++ b/Libraries/LibJS/Tests/Array.prototype.toString.js
@@ -6,6 +6,12 @@ try {
 
     assert("rgb(" + [10, 11, 12] + ")" === "rgb(10,11,12)");
 
+    a = new Array(5);
+    assert(a.toString() === ",,,,");
+    a[2] = "foo";
+    a[4] = "bar";
+    assert(a.toString() === ",,foo,,bar");
+
     console.log("PASS");
 } catch (e) {
     console.log("FAIL: " + e);