diff --git a/.gitignore b/.gitignore
index 94fceeb2..6000c6c3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
+/node_modules/
+/npm-debug.log
 tmp/
-node_modules/
diff --git a/.npmignore b/.npmignore
deleted file mode 100644
index efab07fb..00000000
--- a/.npmignore
+++ /dev/null
@@ -1,2 +0,0 @@
-test
-.travis.yml
diff --git a/.travis.yml b/.travis.yml
index 82460de5..4e046b8f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,10 @@
 language: node_js
 before_install: "npm install -g npm"
 node_js:
-    - "0.10"
+    - "iojs"
+    - "0.12"
     - "0.11"
+    - "0.10"
+matrix:
+  fast_finish: true
+sudo: false
diff --git a/bin/uglifyjs b/bin/uglifyjs
index df7b7832..8851660f 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -132,24 +132,24 @@ normalize(ARGS);
 
 if (ARGS.noerr) {
     UglifyJS.DefaultsError.croak = function(msg, defs) {
-        sys.error("WARN: " + msg);
+        print_error("WARN: " + msg);
     };
 }
 
 if (ARGS.version || ARGS.V) {
     var json = require("../package.json");
-    sys.puts(json.name + ' ' + json.version);
+    print(json.name + ' ' + json.version);
     process.exit(0);
 }
 
 if (ARGS.ast_help) {
     var desc = UglifyJS.describe_ast();
-    sys.puts(typeof desc == "string" ? desc : JSON.stringify(desc, null, 2));
+    print(typeof desc == "string" ? desc : JSON.stringify(desc, null, 2));
     process.exit(0);
 }
 
 if (ARGS.h || ARGS.help) {
-    sys.puts(yargs.help());
+    print(yargs.help());
     process.exit(0);
 }
 
@@ -221,7 +221,7 @@ if (ARGS.comments != null) {
         try {
             OUTPUT_OPTIONS.comments = new RegExp(ARGS.comments.substr(1, regex_pos - 1), ARGS.comments.substr(regex_pos + 1));
         } catch (e) {
-            sys.error("ERROR: Invalid --comments: " + e.message);
+            print_error("ERROR: Invalid --comments: " + e.message);
         }
     } else if (ARGS.comments == "all") {
         OUTPUT_OPTIONS.comments = true;
@@ -241,7 +241,7 @@ var files = ARGS._.slice();
 
 if (ARGS.self) {
     if (files.length > 0) {
-        sys.error("WARN: Ignoring input files since --self was passed");
+        print_error("WARN: Ignoring input files since --self was passed");
     }
     files = UglifyJS.FILES;
     if (!ARGS.wrap) ARGS.wrap = "UglifyJS";
@@ -253,7 +253,7 @@ var ORIG_MAP = ARGS.in_source_map;
 if (ORIG_MAP) {
     ORIG_MAP = JSON.parse(fs.readFileSync(ORIG_MAP));
     if (files.length == 0) {
-        sys.error("INFO: Using file from the input source map: " + ORIG_MAP.file);
+        print_error("INFO: Using file from the input source map: " + ORIG_MAP.file);
         files = [ ORIG_MAP.file ];
     }
     if (ARGS.source_map_root == null) {
@@ -266,12 +266,12 @@ if (files.length == 0) {
 }
 
 if (files.indexOf("-") >= 0 && ARGS.source_map) {
-    sys.error("ERROR: Source map doesn't work with input from STDIN");
+    print_error("ERROR: Source map doesn't work with input from STDIN");
     process.exit(1);
 }
 
 if (files.filter(function(el){ return el == "-" }).length > 1) {
-    sys.error("ERROR: Can read a single file from STDIN (two or more dashes specified)");
+    print_error("ERROR: Can read a single file from STDIN (two or more dashes specified)");
     process.exit(1);
 }
 
@@ -294,9 +294,9 @@ try {
     var compressor = COMPRESS && UglifyJS.Compressor(COMPRESS);
 } catch(ex) {
     if (ex instanceof UglifyJS.DefaultsError) {
-        sys.error(ex.msg);
-        sys.error("Supported options:");
-        sys.error(sys.inspect(ex.defs));
+        print_error(ex.msg);
+        print_error("Supported options:");
+        print_error(sys.inspect(ex.defs));
         process.exit(1);
     }
 }
@@ -304,7 +304,7 @@ try {
 async.eachLimit(files, 1, function (file, cb) {
     read_whole_file(file, function (err, code) {
         if (err) {
-            sys.error("ERROR: can't read file: " + file);
+            print_error("ERROR: can't read file: " + file);
             process.exit(1);
         }
         if (ARGS.p != null) {
@@ -341,9 +341,9 @@ async.eachLimit(files, 1, function (file, cb) {
                     });
                 } catch(ex) {
                     if (ex instanceof UglifyJS.JS_Parse_Error) {
-                        sys.error("Parse error at " + file + ":" + ex.line + "," + ex.col);
-                        sys.error(ex.message);
-                        sys.error(ex.stack);
+                        print_error("Parse error at " + file + ":" + ex.line + "," + ex.col);
+                        print_error(ex.message);
+                        print_error(ex.stack);
                         process.exit(1);
                     }
                     throw ex;
@@ -372,12 +372,13 @@ async.eachLimit(files, 1, function (file, cb) {
         TOPLEVEL = TOPLEVEL.wrap_enclose(arg_parameter_list);
     }
 
-    if (ARGS.mangle_props) (function(){
+    if (ARGS.mangle_props || ARGS.name_cache) (function(){
         var reserved = RESERVED ? RESERVED.props : null;
         var cache = readNameCache("props");
         TOPLEVEL = UglifyJS.mangle_properties(TOPLEVEL, {
-            reserved: reserved,
-            cache: cache
+            reserved   : reserved,
+            cache      : cache,
+            only_cache : !ARGS.mangle_props
         });
         writeNameCache("props", cache);
     })();
@@ -443,15 +444,15 @@ async.eachLimit(files, 1, function (file, cb) {
     if (OUTPUT_FILE) {
         fs.writeFileSync(OUTPUT_FILE, output, "utf8");
     } else {
-        sys.print(output);
+        print(output);
     }
 
     if (ARGS.stats) {
-        sys.error(UglifyJS.string_template("Timing information (compressed {count} files):", {
+        print_error(UglifyJS.string_template("Timing information (compressed {count} files):", {
             count: files.length
         }));
         for (var i in STATS) if (STATS.hasOwnProperty(i)) {
-            sys.error(UglifyJS.string_template("- {name}: {time}s", {
+            print_error(UglifyJS.string_template("- {name}: {time}s", {
                 name: i,
                 time: (STATS[i] / 1000).toFixed(3)
             }));
@@ -478,7 +479,7 @@ function getOptions(x, constants) {
             ast = UglifyJS.parse(x, { expression: true });
         } catch(ex) {
             if (ex instanceof UglifyJS.JS_Parse_Error) {
-                sys.error("Error parsing arguments in: " + x);
+                print_error("Error parsing arguments in: " + x);
                 process.exit(1);
             }
         }
@@ -497,8 +498,8 @@ function getOptions(x, constants) {
                 ret[name] = true;
                 return true;    // no descend
             }
-            sys.error(node.TYPE)
-            sys.error("Error parsing arguments in: " + x);
+            print_error(node.TYPE)
+            print_error("Error parsing arguments in: " + x);
             process.exit(1);
         }));
     }
@@ -530,3 +531,11 @@ function time_it(name, cont) {
     }
     return ret;
 }
+
+function print_error(msg) {
+    console.error("%s", msg);
+}
+
+function print(txt) {
+    console.log("%s", txt);
+}
diff --git a/lib/compress.js b/lib/compress.js
index fa89c322..530e7c2f 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1168,12 +1168,12 @@ merge(Compressor.prototype, {
                             return make_node(AST_EmptyStatement, node);
                         }
                         if (def.length == 0) {
-                            return side_effects;
+                            return in_list ? MAP.splice(side_effects.body) : side_effects;
                         }
                         node.definitions = def;
                         if (side_effects) {
                             side_effects.body.unshift(node);
-                            node = side_effects;
+                            return in_list ? MAP.splice(side_effects.body) : side_effects;
                         }
                         return node;
                     }
@@ -2272,14 +2272,6 @@ merge(Compressor.prototype, {
         });
     });
 
-    OPT(AST_NaN, function (self, compressor) {
-        return make_node(AST_Binary, self, {
-            operator : '/',
-            left     : make_node(AST_Number, self, {value: 0}),
-            right    : make_node(AST_Number, self, {value: 0})
-        });
-    });
-
     OPT(AST_Undefined, function(self, compressor){
         if (compressor.option("unsafe")) {
             var scope = compressor.find_parent(AST_Scope);
@@ -2364,6 +2356,7 @@ merge(Compressor.prototype, {
         if (consequent instanceof AST_Call
             && alternative.TYPE === consequent.TYPE
             && consequent.args.length == alternative.args.length
+            && !consequent.expression.has_side_effects(compressor)
             && consequent.expression.equivalent_to(alternative.expression)) {
             if (consequent.args.length == 0) {
                 return make_node(AST_Seq, self, {
diff --git a/lib/output.js b/lib/output.js
index 8271a6f7..cb743bd6 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -176,7 +176,6 @@ function OutputStream(options) {
                     might_need_space = false;
             }
             might_need_semicolon = false;
-            maybe_newline();
         }
 
         if (!options.beautify && options.preserve_line && stack[stack.length - 1]) {
diff --git a/lib/parse.js b/lib/parse.js
index 0323d2cc..f1874b30 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -110,7 +110,7 @@ var OPERATORS = makePredicate([
     "||"
 ]);
 
-var WHITESPACE_CHARS = makePredicate(characters(" \u00a0\n\r\t\f\u000b\u200b\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u202f\u205f\u3000"));
+var WHITESPACE_CHARS = makePredicate(characters(" \u00a0\n\r\t\f\u000b\u200b\u180e\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u202f\u205f\u3000\uFEFF"));
 
 var PUNC_BEFORE_EXPRESSION = makePredicate(characters("[{(,.;:"));
 
@@ -215,7 +215,7 @@ var EX_EOF = {};
 function tokenizer($TEXT, filename, html5_comments) {
 
     var S = {
-        text            : $TEXT.replace(/\uFEFF/g, ''),
+        text            : $TEXT,
         filename        : filename,
         pos             : 0,
         tokpos          : 0,
@@ -356,8 +356,13 @@ function tokenizer($TEXT, filename, html5_comments) {
           case 120 : return String.fromCharCode(hex_bytes(2)); // \x
           case 117 : return String.fromCharCode(hex_bytes(4)); // \u
           case 10  : return ""; // newline
-          default  : return ch;
+          case 13  :            // \r
+            if (peek() == "\n") { // DOS newline
+                next(true, in_string);
+                return "";
+            }
         }
+        return ch;
     };
 
     function hex_bytes(n) {
@@ -374,7 +379,7 @@ function tokenizer($TEXT, filename, html5_comments) {
     var read_string = with_eof_error("Unterminated string constant", function(quote_char){
         var quote = next(), ret = "";
         for (;;) {
-            var ch = next(true);
+            var ch = next(true, true);
             if (ch == "\\") {
                 // read OctalEscapeSequence (XXX: deprecated if "strict mode")
                 // https://github.com/mishoo/UglifyJS/issues/178
diff --git a/lib/propmangle.js b/lib/propmangle.js
index 46fb7521..0890eaa7 100644
--- a/lib/propmangle.js
+++ b/lib/propmangle.js
@@ -63,7 +63,8 @@ function find_builtins() {
 function mangle_properties(ast, options) {
     options = defaults(options, {
         reserved : null,
-        cache : null
+        cache : null,
+        only_cache : false
     });
 
     var reserved = options.reserved;
@@ -140,11 +141,15 @@ function mangle_properties(ast, options) {
 
     function can_mangle(name) {
         if (reserved.indexOf(name) >= 0) return false;
+        if (options.only_cache) {
+            return cache.props.has(name);
+        }
         if (/^[0-9.]+$/.test(name)) return false;
         return true;
     }
 
     function should_mangle(name) {
+        if (reserved.indexOf(name) >= 0) return false;
         return cache.props.has(name)
             || names_to_mangle.indexOf(name) >= 0;
     }
diff --git a/package.json b/package.json
index aaa4359d..27f8c857 100644
--- a/package.json
+++ b/package.json
@@ -1,37 +1,51 @@
 {
   "name": "uglify-js",
   "description": "JavaScript parser, mangler/compressor and beautifier toolkit",
-    "homepage": "http://lisperator.net/uglifyjs",
-    "main": "tools/node.js",
-    "version": "2.4.20",
-    "engines": { "node" : ">=0.4.0" },
-    "maintainers": [{
-        "name": "Mihai Bazon",
-        "email": "mihai.bazon@gmail.com",
-        "web": "http://lisperator.net/"
-    }],
-    "repository": {
-        "type": "git",
-        "url": "https://github.com/mishoo/UglifyJS2.git"
-    },
-    "dependencies": {
-        "async"      : "~0.2.6",
-        "source-map" : "0.1.34",
-        "yargs": "~3.5.4",
-        "uglify-to-browserify": "~1.0.0"
-    },
-    "devDependencies": {
-        "acorn": "~0.6.0",
-        "escodegen": "~1.3.3",
-        "esfuzz": "~0.3.1",
-        "estraverse": "~1.5.1"
-    },
-    "browserify": {
-        "transform": [ "uglify-to-browserify" ]
-    },
-    "bin": {
-        "uglifyjs" : "bin/uglifyjs"
-    },
-    "license": "BSD",
-    "scripts": {"test": "node test/run-tests.js"}
+  "homepage": "http://lisperator.net/uglifyjs",
+  "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
+  "license": "BSD",
+  "version": "2.4.23",
+  "engines": {
+    "node": ">=0.4.0"
+  },
+  "maintainers": [
+    "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)"
+  ],
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/mishoo/UglifyJS2.git"
+  },
+  "bugs": {
+    "url": "https://github.com/mishoo/UglifyJS2/issues"
+  },
+  "main": "tools/node.js",
+  "bin": {
+    "uglifyjs": "bin/uglifyjs"
+  },
+  "files": [
+    "bin",
+    "lib",
+    "tools",
+    "LICENSE"
+  ],
+  "dependencies": {
+    "async": "~0.2.6",
+    "source-map": "0.1.34",
+    "uglify-to-browserify": "~1.0.0",
+    "yargs": "~3.5.4"
+  },
+  "devDependencies": {
+    "acorn": "~0.6.0",
+    "escodegen": "~1.3.3",
+    "esfuzz": "~0.3.1",
+    "estraverse": "~1.5.1"
+  },
+  "browserify": {
+    "transform": [
+      "uglify-to-browserify"
+    ]
+  },
+  "scripts": {
+    "test": "node test/run-tests.js"
+  }
 }
diff --git a/test/compress/conditionals.js b/test/compress/conditionals.js
index 299097be..1b961812 100644
--- a/test/compress/conditionals.js
+++ b/test/compress/conditionals.js
@@ -153,6 +153,7 @@ cond_1: {
         conditionals: true
     };
     input: {
+        var do_something; // if undeclared it's assumed to have side-effects
         if (some_condition()) {
             do_something(x);
         } else {
@@ -160,6 +161,7 @@ cond_1: {
         }
     }
     expect: {
+        var do_something;
         do_something(some_condition() ? x : y);
     }
 }
@@ -169,7 +171,7 @@ cond_2: {
         conditionals: true
     };
     input: {
-        var x;
+        var x, FooBar;
         if (some_condition()) {
             x = new FooBar(1);
         } else {
@@ -177,7 +179,7 @@ cond_2: {
         }
     }
     expect: {
-        var x;
+        var x, FooBar;
         x = new FooBar(some_condition() ? 1 : 2);
     }
 }
@@ -187,6 +189,7 @@ cond_3: {
         conditionals: true
     };
     input: {
+        var FooBar;
         if (some_condition()) {
             new FooBar(1);
         } else {
@@ -194,6 +197,7 @@ cond_3: {
         }
     }
     expect: {
+        var FooBar;
         some_condition() ? new FooBar(1) : FooBar(2);
     }
 }
@@ -203,6 +207,7 @@ cond_4: {
         conditionals: true
     };
     input: {
+        var do_something;
         if (some_condition()) {
             do_something();
         } else {
@@ -210,6 +215,7 @@ cond_4: {
         }
     }
     expect: {
+        var do_something;
         some_condition(), do_something();
     }
 }
diff --git a/test/compress/issue-597.js b/test/compress/issue-597.js
index 3c651a4c..f243223a 100644
--- a/test/compress/issue-597.js
+++ b/test/compress/issue-597.js
@@ -6,7 +6,7 @@ NaN_and_Infinity_must_have_parens: {
     }
     expect: {
         (1/0).toString();
-        (0/0).toString();
+        NaN.toString();         // transformation to 0/0 dropped
     }
 }
 
diff --git a/test/run-tests.js b/test/run-tests.js
index 94bf6ad9..215f6af8 100755
--- a/test/run-tests.js
+++ b/test/run-tests.js
@@ -84,7 +84,12 @@ function run_compress_tests() {
                 warnings: false
             });
             var cmp = new U.Compressor(options, true);
-            var expect = make_code(as_toplevel(test.expect), false);
+            var expect;
+            if (test.expect) {
+                expect = make_code(as_toplevel(test.expect), false);
+            } else {
+                expect = test.expect_exact;
+            }
             var input = as_toplevel(test.input);
             var input_code = make_code(test.input);
             var output = input.transform(cmp);
@@ -150,7 +155,7 @@ function parse_test(file) {
             }
             if (node instanceof U.AST_LabeledStatement) {
                 assert.ok(
-                    node.label.name == "input" || node.label.name == "expect",
+                    node.label.name == "input" || node.label.name == "expect" || node.label.name == "expect_exact",
                     tmpl("Unsupported label {name} [{line},{col}]", {
                         name: node.label.name,
                         line: node.label.start.line,
@@ -162,7 +167,16 @@ function parse_test(file) {
                     if (stat.body.length == 1) stat = stat.body[0];
                     else if (stat.body.length == 0) stat = new U.AST_EmptyStatement();
                 }
-                test[node.label.name] = stat;
+                if (node.label.name === "expect_exact") {
+                    if (!(stat.TYPE === "SimpleStatement" && stat.body.TYPE === "String")) {
+                        throw new Error(
+                            "The value of the expect_exact clause should be a string, " +
+                            "like `expect_exact: \"some.exact.javascript;\"`");
+                    }
+                    test[node.label.name] = stat.body.start.value
+                } else {
+                    test[node.label.name] = stat;
+                }
                 return true;
             }
         });
diff --git a/tools/node.js b/tools/node.js
index 054a05c0..cbe49e39 100644
--- a/tools/node.js
+++ b/tools/node.js
@@ -1,10 +1,8 @@
 var path = require("path");
 var fs = require("fs");
 var vm = require("vm");
-var sys = require("util");
 
 var UglifyJS = vm.createContext({
-    sys           : sys,
     console       : console,
     process       : process,
     Buffer        : Buffer,
@@ -19,7 +17,7 @@ function load_global(file) {
     } catch(ex) {
         // XXX: in case of a syntax error, the message is kinda
         // useless. (no location information).
-        sys.debug("ERROR in file: " + file + " / " + ex);
+        console.log("ERROR in file: " + file + " / " + ex);
         process.exit(1);
     }
 };
@@ -42,7 +40,7 @@ var FILES = exports.FILES = [
 FILES.forEach(load_global);
 
 UglifyJS.AST_Node.warn_function = function(txt) {
-    sys.error("WARN: " + txt);
+    console.error("WARN: %s", txt);
 };
 
 // XXX: perhaps we shouldn't export everything but heck, I'm lazy.