From 3d68105b2cac175a917f6c235e33e52e510e47da Mon Sep 17 00:00:00 2001
From: Alex Zaytsev <hazzik@gmail.com>
Date: Wed, 2 Sep 2020 14:29:31 +1200
Subject: [PATCH] Optimize wrapper

---
 jsfuck.js           | 31 ++++++++++++++++++++++++++++---
 test/jsfuck_test.js |  5 +++++
 2 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/jsfuck.js b/jsfuck.js
index 8f5f2336..ef5147d0 100644
--- a/jsfuck.js
+++ b/jsfuck.js
@@ -239,6 +239,10 @@
     }
   }
 
+  function escapeSequenceForReplace(c) {
+    return escapeSequence(c).replace('\\', 't');
+  }
+
   function encode(input, wrapWithEval, runInParentScope){
     var output = [];
 
@@ -254,8 +258,24 @@
     }
     unmappped = unmappped.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
     unmappped = new RegExp('[^' + unmappped + ']','g');
-    var hasUnmappedCharacters = unmappped.test(input);
-    if (hasUnmappedCharacters) {
+    var unmappedCharactersCount = (input.match(unmappped) || []).length;
+    if (unmappedCharactersCount > 1) {
+      // Without this optimization one unmapped caracter has encoded length
+      // of about 3600 characters. Every additional unmapped character adds 
+      // 2000 to the total length. For example, the lenght of `~` is 3605, 
+      // `~~` is 5600, and `~~~` is 7595.
+      // 
+      // The loader with replace has encoded length of about 5300 characters
+      // and every additional character adds 100 to the total length. 
+      // In the same example the length of `~~` becomes 5371 and `~~~` -- 5463.
+      // 
+      // So, when we have more than one unmapped character we want to encode whole input
+      // except select characters (that have encoded length less than about 70)
+      // into an escape sequence.
+      //
+      // NOTE: `t` should be escaped!
+      input = input.replace(/[^0123456789.adefilnrsuN]/g, escapeSequenceForReplace);
+    } else if (unmappedCharactersCount > 0) {
       //Because we will wrap the input into a string we need to escape Backslash 
       // and Double quote characters (we do not need to worry about other characters 
       // because they are not mapped explicitly).
@@ -295,7 +315,12 @@
       output += "+[]";
     }
 
-    if (hasUnmappedCharacters) {
+    if (unmappedCharactersCount > 1) {
+      // replace `t` with `\\`
+      output = "(" + output + ")[" + encode("split") + "](" + encode ("t") + ")[" + encode("join") +"](" + encode("\\") + ")";
+    }
+
+    if (unmappedCharactersCount > 0) {
       output = "[][" + encode("flat") + "]"+
       "[" + encode("constructor") + "]" +
       "(" + encode("return\"") + "+" + output + "+" + encode("\"") + ")()";
diff --git a/test/jsfuck_test.js b/test/jsfuck_test.js
index 2bf6dfca..0c0cbfc8 100644
--- a/test/jsfuck_test.js
+++ b/test/jsfuck_test.js
@@ -63,6 +63,11 @@ createTest('NaNtrue');
 createTest('trueNaN');
 createTest('undefinedNaN');
 createTest('~\\"');
+createTest('t~');
+createTest('~t');
+createTest('[(~t~)]');
+createTest('~0123456789 abcdefghijklmnopqrstuvwxyz()+.~');
+createTest('~0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ()+.~');
 
 for(var i=MIN; i<MAX ;i++) {
 	createTest(String.fromCharCode(i));