Merge 352bdaecb6 into 491f16c766

README.md

@@ -428,9 +428,13 @@ to set `true`; it's effectively a shortcut for `foo=true`).
   such as `console.info` and/or retain side effects from function arguments
   after dropping the function call then use `pure_funcs` instead.
 
+- `drop_error` -- default `false`.  Pass `true` to discard description
+  of Error() calls.
+
 - `expression` -- default `false`.  Pass `true` to preserve completion values
   from terminal statements without `return`, e.g. in bookmarklets.
 
+
 - `keep_fargs` -- default `true`.  Prevents the
   compressor from discarding unused function arguments.  You need this
   for code which relies on `Function.length`.

lib/compress.js

@@ -79,6 +79,7 @@ function Compressor(options, false_by_default) {
         negate_iife   : !false_by_default,
         screw_ie8     : true,
         drop_console  : false,
+        drop_error    : false,
         angular       : false,
         expression    : false,
         warnings      : true,
@@ -2854,6 +2855,22 @@ merge(Compressor.prototype, {
                 }
             }
         }
+        if (compressor.option("drop_error")) {
+            var exp = self.expression;
+            if (exp instanceof AST_SymbolRef
+                && (exp.name == "Error" || 
+                    exp.name == "EvalError" || 
+                    exp.name == "InternalError" || 
+                    exp.name == "RangeError" || 
+                    exp.name == "ReferenceError" || 
+                    exp.name == "SyntaxError" || 
+                    exp.name == "TypeError" || 
+                    exp.name == "URIError")
+                && exp.undeclared()) {
+                   // drop error description(s)
+                   self.args = [];
+                }
+        }
         if (exp instanceof AST_Function) {
             if (exp.body[0] instanceof AST_Return) {
                 var value = exp.body[0].value;
@@ -2891,6 +2908,23 @@ merge(Compressor.prototype, {
     });
 
     OPT(AST_New, function(self, compressor){
+
+        if (compressor.option("drop_error")) {
+            var exp = self.expression;
+            if (exp instanceof AST_SymbolRef
+                && (exp.name == "Error" || 
+                    exp.name == "EvalError" || 
+                    exp.name == "InternalError" || 
+                    exp.name == "RangeError" || 
+                    exp.name == "ReferenceError" || 
+                    exp.name == "SyntaxError" || 
+                    exp.name == "TypeError" || 
+                    exp.name == "URIError")
+                && exp.undeclared()) {
+                   // drop error description(s)
+                   self.args = [];
+                }
+        }
         if (compressor.option("unsafe")) {
             var exp = self.expression;
             if (exp instanceof AST_SymbolRef && exp.undeclared()) {
@@ -2899,6 +2933,12 @@ merge(Compressor.prototype, {
                   case "RegExp":
                   case "Function":
                   case "Error":
+                  case "EvalError":
+                  case "InternalError":
+                  case "RangeError":
+                  case "ReferenceError":
+                  case "SyntaxError":
+                  case "URIError":
                   case "Array":
                     return make_node(AST_Call, self, self).transform(compressor);
                 }

test/compress/drop-error.js

@@ -0,0 +1,80 @@
+drop_error_1: {
+    options = {};
+    input: {
+        Error('foo');
+        Error('foo', arguments);
+        EvalError('foo');
+        EvalError('foo', arguments);
+        InternalError('foo');
+        InternalError('foo', arguments);
+        RangeError('foo');
+        RangeError('foo', arguments);
+        ReferenceError('foo');
+        ReferenceError('foo', arguments);
+        SyntaxError('foo');
+        SyntaxError('foo', arguments);
+        TypeError('foo');
+        TypeError('foo', arguments);
+        URIError('foo');
+        URIError('foo', arguments);
+
+    }
+    expect: {
+        Error('foo');
+        Error('foo', arguments);
+        EvalError('foo');
+        EvalError('foo', arguments);
+        InternalError('foo');
+        InternalError('foo', arguments);
+        RangeError('foo');
+        RangeError('foo', arguments);
+        ReferenceError('foo');
+        ReferenceError('foo', arguments);
+        SyntaxError('foo');
+        SyntaxError('foo', arguments);
+        TypeError('foo');
+        TypeError('foo', arguments);
+        URIError('foo');
+        URIError('foo', arguments);
+    }
+}
+
+drop_error_2: {
+    options = { drop_error: true };
+    input: {
+        Error('foo');
+        Error('foo', arguments);
+        EvalError('foo');
+        EvalError('foo', arguments);
+        InternalError('foo');
+        InternalError('foo', arguments);
+        RangeError('foo');
+        RangeError('foo', arguments);
+        ReferenceError('foo');
+        ReferenceError('foo', arguments);
+        SyntaxError('foo');
+        SyntaxError('foo', arguments);
+        TypeError('foo');
+        TypeError('foo', arguments);
+        URIError('foo');
+        URIError('foo', arguments);
+    }
+    expect: {
+        Error();
+        Error();
+        EvalError();
+        EvalError();
+        InternalError();
+        InternalError();
+        RangeError();
+        RangeError();
+        ReferenceError();
+        ReferenceError();
+        SyntaxError();
+        SyntaxError();
+        TypeError();
+        TypeError();
+        URIError();
+        URIError();
+    }
+}