repl: do not consider ... as a REPL command

This fix makes ... in REPL to be considered as a javascript construct
rather than a REPL keyword.

Fixes: #14426
Backport-PR-URL: #14915
PR-URL: #14467
Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

lib/repl.js

@@ -519,10 +519,11 @@ function REPLServer(prompt,
 
     // Check to see if a REPL keyword was used. If it returns true,
     // display next prompt and return.
-    if (cmd && cmd.charAt(0) === '.' && isNaN(parseFloat(cmd))) {
-      var matches = cmd.match(/^\.([^\s]+)\s*(.*)$/);
-      var keyword = matches && matches[1];
-      var rest = matches && matches[2];
+    if (cmd && cmd.charAt(0) === '.' && cmd.charAt(1) !== '.' &&
+        isNaN(parseFloat(cmd))) {
+      const matches = cmd.match(/^\.([^\s]+)\s*(.*)$/);
+      const keyword = matches && matches[1];
+      const rest = matches && matches[2];
       if (self.parseREPLKeyword(keyword, rest) === true) {
         return;
       } else if (!self.bufferedCommand) {

test/parallel/test-repl.js

@@ -387,7 +387,13 @@ function error_test() {
     {
       client: client_unix, send: '(function() {\nif (false) {} /bar"/;\n}())',
       expect: `${prompt_multiline}${prompt_multiline}undefined\n${prompt_unix}`
-    }
+    },
+    // Do not parse `...[]` as a REPL keyword
+    { client: client_unix, send: '...[]\n',
+      expect: `${prompt_multiline}` },
+    // bring back the repl to prompt
+    { client: client_unix, send: '.break',
+      expect: `${prompt_unix}` }
   ]);
 }