From b77996b69b44a26b8685914a6de39c1408670ae1 Mon Sep 17 00:00:00 2001
From: "weiran.zsd" <weiran.zsd@alibaba-inc.com>
Date: Thu, 22 Mar 2018 00:27:09 +0800
Subject: [PATCH] Fix: no-invalid-regexp not understand variable for flags
 (fixes #10112)

---
 lib/rules/no-invalid-regexp.js       | 15 ++++++---------
 tests/lib/rules/no-invalid-regexp.js |  1 +
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/lib/rules/no-invalid-regexp.js b/lib/rules/no-invalid-regexp.js
index e57029c9f82..7169e0ca770 100644
--- a/lib/rules/no-invalid-regexp.js
+++ b/lib/rules/no-invalid-regexp.js
@@ -98,20 +98,17 @@ module.exports = {
                     return;
                 }
                 const pattern = node.arguments[0].value;
-                let flags = "";
+                let flags = isString(node.arguments[1]) ? node.arguments[1].value : "";
 
-                if (node.arguments[1]) {
-                    flags = isString(node.arguments[1]) ? node.arguments[1].value : null;
-                    if (allowedFlags) {
-                        flags = flags.replace(allowedFlags, "");
-                    }
+                if (allowedFlags) {
+                    flags = flags.replace(allowedFlags, "");
                 }
 
                 // If flags are unknown, check both are errored or not.
                 const message = validateRegExpFlags(flags) || (
-                    (flags === null)
-                        ? validateRegExpPattern(pattern, true) && validateRegExpPattern(pattern, false)
-                        : validateRegExpPattern(pattern, flags.indexOf("u") !== -1)
+                    flags
+                        ? validateRegExpPattern(pattern, flags.indexOf("u") !== -1)
+                        : validateRegExpPattern(pattern, true) && validateRegExpPattern(pattern, false)
                 );
 
                 if (message) {
diff --git a/tests/lib/rules/no-invalid-regexp.js b/tests/lib/rules/no-invalid-regexp.js
index 3b9dac536bd..305f4e0d383 100644
--- a/tests/lib/rules/no-invalid-regexp.js
+++ b/tests/lib/rules/no-invalid-regexp.js
@@ -23,6 +23,7 @@ ruleTester.run("no-invalid-regexp", rule, {
         "new RegExp",
         "new RegExp('.', 'im')",
         "global.RegExp('\\\\')",
+        "new RegExp('.', y)",
         { code: "new RegExp('.', 'y')", options: [{ allowConstructorFlags: ["y"] }] },
         { code: "new RegExp('.', 'u')", options: [{ allowConstructorFlags: ["U"] }] },
         { code: "new RegExp('.', 'yu')", options: [{ allowConstructorFlags: ["y", "u"] }] },