Enable --screw-ie8 by default.

catch identifier is mangled correctly for ES5 standards-compliant JS engines by default.

Unconditionally use the ie8 if/do-while workaround whether or not --screw-ie8 is enabled.

To support non-standard ie8 javascript use: uglifyjs --support-ie8

1 files changed, 13 insertions, 7 deletions

diff --git a/bin/uglifyjs b/bin/uglifyjs
index b7009426..30d234fd 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -10,6 +10,7 @@ var fs = require("fs");
 var path = require("path");
 var async = require("async");
 var acorn;
+var screw_ie8 = true;
 var ARGS = yargs
     .usage("$0 input1.js [input2.js ...] [options]\n\
 Use a single dash to read input from the standard input.\
@@ -24,7 +25,8 @@ mangling you need to use `-c` and `-m`.\
     .describe("source-map-url", "The path to the source map to be added in //# sourceMappingURL.  Defaults to the value passed with --source-map.")
     .describe("source-map-include-sources", "Pass this flag if you want to include the content of source files in the source map as sourcesContent property.")
     .describe("in-source-map", "Input source map, useful if you're compressing JS that was generated from some other original code.")
-    .describe("screw-ie8", "Pass this flag if you don't care about full compliance with Internet Explorer 6-8 quirks (by default UglifyJS will try to be IE-proof).")
+    .describe("screw-ie8", "Do not support Internet Explorer 6-8 quirks. This flag is enabled by default.")
+    .describe("support-ie8", "Support non-standard Internet Explorer 6-8 javascript. Note: may break standards compliant `catch` identifiers.")
     .describe("expr", "Parse a single expression, rather than a program (for parsing JSON)")
     .describe("p", "Skip prefix for original filenames that appear in source maps. \
 For example -p 3 will drop 3 directories from file names and ensure they are relative paths. \
@@ -105,12 +107,14 @@ You need to pass an argument to this option to specify the name that your module
     .string("p")
     .string("prefix")
     .string("name-cache")
+
     .array("reserved-file")
     .array("pure-funcs")
 
     .boolean("expr")
     .boolean("source-map-include-sources")
     .boolean("screw-ie8")
+    .boolean("support-ie8")
     .boolean("export-all")
     .boolean("self")
     .boolean("v")
@@ -230,12 +234,14 @@ if (ARGS.mangle_props == 2) {
         COMPRESS.properties = false;
 }
 
-if (ARGS.screw_ie8) {
-    if (COMPRESS) COMPRESS.screw_ie8 = true;
-    if (MANGLE) MANGLE.screw_ie8 = true;
-    OUTPUT_OPTIONS.screw_ie8 = true;
+if (ARGS.support_ie8 === true && ARGS.screw_ie8 !== true) {
+    screw_ie8 = false;
 }
 
+if (COMPRESS) COMPRESS.screw_ie8 = screw_ie8;
+if (MANGLE) MANGLE.screw_ie8 = screw_ie8;
+OUTPUT_OPTIONS.screw_ie8 = screw_ie8;
+
 if (ARGS.keep_fnames) {
     if (COMPRESS) COMPRESS.keep_fnames = true;
     if (MANGLE) MANGLE.keep_fnames = true;
@@ -426,7 +432,7 @@ async.eachLimit(files, 1, function (file, cb) {
 
     if (SCOPE_IS_NEEDED) {
         time_it("scope", function(){
-            TOPLEVEL.figure_out_scope({ screw_ie8: ARGS.screw_ie8, cache: TL_CACHE });
+            TOPLEVEL.figure_out_scope({ screw_ie8: screw_ie8, cache: TL_CACHE });
             if (ARGS.lint) {
                 TOPLEVEL.scope_warnings();
             }
@@ -441,7 +447,7 @@ async.eachLimit(files, 1, function (file, cb) {
 
     if (SCOPE_IS_NEEDED) {
         time_it("scope", function(){
-            TOPLEVEL.figure_out_scope({ screw_ie8: ARGS.screw_ie8, cache: TL_CACHE });
+            TOPLEVEL.figure_out_scope({ screw_ie8: screw_ie8, cache: TL_CACHE });
             if (MANGLE && !TL_CACHE) {
                 TOPLEVEL.compute_char_frequency(MANGLE);
             }