nodejs
diff --git a/‎lib/buffer.js‎
Lines changed: 40 additions & 9 deletions b/‎lib/buffer.js‎
Lines changed: 40 additions & 9 deletions
@@ -51,6 +51,7 @@ const {
   TypedArrayPrototypeGetLength,
   TypedArrayPrototypeSet,
   TypedArrayPrototypeSlice,
+  TypedArrayPrototypeSubarray,
   Uint8Array,
   Uint8ArrayPrototype,
 } = primordials;
@@ -626,25 +627,55 @@ Buffer.concat = function concat(list, length) {
   if (length === undefined) {
     length = 0;
     for (let i = 0; i < list.length; i++) {
-      if (list[i].length) {
-        length += list[i].length;
+      const buf = list[i];
+      if (!isUint8Array(buf)) {
+        // TODO(BridgeAR): This should not be of type ERR_INVALID_ARG_TYPE.
+        // Instead, find the proper error code for this.
+        throw new ERR_INVALID_ARG_TYPE(
+          `list[${i}]`, ['Buffer', 'Uint8Array'], buf);
       }
+      length += TypedArrayPrototypeGetByteLength(buf);
     }
-  } else {
-    validateOffset(length, 'length');
+
+    const buffer = allocate(length);
+    let pos = 0;
+    for (let i = 0; i < list.length; i++) {
+      const buf = list[i];
+      const bufLength = TypedArrayPrototypeGetByteLength(buf);
+      TypedArrayPrototypeSet(buffer, buf, pos);
+      pos += bufLength;
+    }
+
+    if (pos < length) {
+      TypedArrayPrototypeFill(buffer, 0, pos, length);
+    }
+    return buffer;
   }
 
-  const buffer = Buffer.allocUnsafe(length);
-  let pos = 0;
+  validateOffset(length, 'length');
   for (let i = 0; i < list.length; i++) {
-    const buf = list[i];
-    if (!isUint8Array(buf)) {
+    if (!isUint8Array(list[i])) {
       // TODO(BridgeAR): This should not be of type ERR_INVALID_ARG_TYPE.