From 5e76065c9e12f77bbc39b426ee7068bdd6a0056a Mon Sep 17 00:00:00 2001
From: Dan Wolff <dan.d.wolff@gmail.com>
Date: Sun, 4 Feb 2018 22:36:52 +0100
Subject: [PATCH] more efficient to check option and operator only once

---
 lib/compress.js | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index 66b7f037..4a4a3f2d 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4797,6 +4797,7 @@ merge(Compressor.prototype, {
         if (compressor.option("comparisons")) switch (self.operator) {
           case "===":
           case "!==":
+            var is_strict_comparison = true;
             if ((self.left.is_string(compressor) && self.right.is_string(compressor)) ||
                 (self.left.is_number(compressor) && self.right.is_number(compressor)) ||
                 (self.left.is_boolean() && self.right.is_boolean()) ||
@@ -4827,6 +4828,11 @@ merge(Compressor.prototype, {
                 && is_object(self.left.fixed_value())) {
                 return make_node(self.operator[0] == "=" ? AST_True : AST_False, self);
             }
+            // void 0 == x => null == x
+            else if (!is_strict_comparison
+                && is_undefined(self.left, compressor)) {
+                self.left = make_node(AST_Null, self.left);
+            }
             break;
           case "&&":
           case "||":
@@ -4858,12 +4864,6 @@ merge(Compressor.prototype, {
             }
             break;
         }
-        // void 0 == x => null == x
-        if (compressor.option("comparisons") &&
-            (self.operator == "==" || self.operator == "!=") &&
-            is_undefined(self.left, compressor)) {
-            self.left = make_node(AST_Null, self.left);
-        }
         if (self.operator == "+" && compressor.in_boolean_context()) {
             var ll = self.left.evaluate(compressor);
             var rr = self.right.evaluate(compressor);