michaelficarra's suggestion to make object comprehensions' hasOwnProperty check a continue, instead of a wrapped if.

lib/grammar.js

@@ -610,7 +610,8 @@
   operators = [["left", '?'], ["nonassoc", 'UMINUS', 'UPLUS', '!', '!!', '~', '++', '--'], ["left", '*', '/', '%'], ["left", '+', '-'], ["left", '<<', '>>', '>>>'], ["left", '&', '|', '^'], ["left", '<=', '<', '>', '>='], ["right", 'DELETE', 'INSTANCEOF', 'TYPEOF'], ["left", '==', '!='], ["left", '&&', '||', 'OP?'], ["right", '-=', '+=', '/=', '*=', '%=', '||=', '&&=', '?='], ["left", '.'], ["right", 'INDENT'], ["left", 'OUTDENT'], ["right", 'WHEN', 'LEADING_WHEN', 'IN', 'OF', 'BY', 'THROW'], ["right", 'FOR', 'WHILE', 'UNTIL', 'LOOP', 'NEW', 'SUPER', 'CLASS'], ["left", 'EXTENDS'], ["right", 'ASSIGN', 'RETURN'], ["right", '->', '=>', 'UNLESS', 'IF', 'ELSE']];
   tokens = [];
   _a = grammar;
-  for (name in _a) { if (__hasProp.call(_a, name)) {
+  for (name in _a) {
+    if (!__hasProp.call(_a, name)) continue;
     alternatives = _a[name];
     grammar[name] = (function() {
       _b = []; _d = alternatives;
@@ -632,7 +633,7 @@
       }
       return _b;
     })();
-  }}
+  }
   exports.parser = new Parser({
     tokens: tokens.join(' '),
     bnf: grammar,

lib/index.js

@@ -2,8 +2,9 @@
   var _a, key, val;
   var __hasProp = Object.prototype.hasOwnProperty;
   _a = require('./coffee-script');
-  for (key in _a) { if (__hasProp.call(_a, key)) {
+  for (key in _a) {
+    if (!__hasProp.call(_a, key)) continue;
     val = _a[key];
     (exports[key] = val);
-  }}
+  }
 })();

lib/nodes.js

@@ -1393,7 +1393,7 @@
       return '';
     };
     ForNode.prototype.compileNode = function(o) {
-      var body, close, codeInBody, forPart, index, ivar, lvar, name, namePart, range, returnResult, rvar, scope, source, sourcePart, stepPart, svar, topLevel, varPart, vars;
+      var body, codeInBody, forPart, guardPart, index, ivar, lvar, name, namePart, range, returnResult, rvar, scope, source, sourcePart, stepPart, svar, topLevel, varPart, vars;
       topLevel = del(o, 'top') && !this.returns;
       range = this.source instanceof ValueNode && this.source.base instanceof RangeNode && !this.source.properties.length;
       source = range ? this.source.base : this.source;
@@ -1422,6 +1422,7 @@
         }
       })();
       varPart = '';
+      guardPart = '';
       body = Expressions.wrap([this.body]);
       if (range) {
         sourcePart = source.compileVariables(o);
@@ -1469,14 +1470,18 @@
       } else {
         varPart = (namePart || '') && (this.pattern ? namePart : ("" + (this.idt(1)) + namePart + ";\n"));
       }
-      this.object ? this.raw ? (forPart = ("" + ivar + " in " + svar)) : (forPart = ("" + ivar + " in " + svar + ") { if (" + (utility('hasProp')) + ".call(" + svar + ", " + ivar + ")")) : null;
+      if (this.object) {
+        forPart = ("" + ivar + " in " + svar);
+        if (!(this.raw)) {
+          guardPart = ("\n" + (this.idt(1)) + "if (!" + (utility('hasProp')) + ".call(" + svar + ", " + ivar + ")) continue;");
+        }
+      }
       body = body.compile(merge(o, {
         indent: this.idt(1),
         top: true
       }));
       vars = range ? name : ("" + name + ", " + ivar);
-      close = this.object && !this.raw ? '}}' : '}';
-      return "" + (sourcePart) + "for (" + forPart + ") {\n" + varPart + body + "\n" + this.tab + close + returnResult;
+      return "" + (sourcePart) + "for (" + forPart + ") {" + guardPart + "\n" + varPart + body + "\n" + this.tab + "}" + returnResult;
     };
     return ForNode;
   })();

lib/rewriter.js

@@ -281,10 +281,11 @@
       })(this));
       unclosed = (function() {
         _c = []; _d = levels;
-        for (key in _d) { if (__hasProp.call(_d, key)) {
+        for (key in _d) {
+          if (!__hasProp.call(_d, key)) continue;
           value = _d[key];
           value > 0 ? _c.push(key) : null;
-        }}
+        }
         return _c;
       })();
       if (unclosed.length) {
@@ -298,10 +299,11 @@
       stack = [];
       debt = {};
       _c = INVERSES;
-      for (key in _c) { if (__hasProp.call(_c, key)) {
+      for (key in _c) {
+        if (!__hasProp.call(_c, key)) continue;
         val = _c[key];
         (debt[key] = 0);
-      }}
+      }
       return this.scanTokens((function(__this) {
         var __func = function(prev, token, post, i) {
           var inv, match, mtag, oppos, tag;

lib/scope.js

@@ -31,12 +31,13 @@
     Scope.prototype.any = function(fn) {
       var _a, k, v;
       _a = this.variables;
-      for (v in _a) { if (__hasProp.call(_a, v)) {
+      for (v in _a) {
+        if (!__hasProp.call(_a, v)) continue;
         k = _a[v];
         if (fn(v, k)) {
           return true;
         }
-      }}
+      }
       return false;
     };
     Scope.prototype.parameter = function(name) {
@@ -79,20 +80,22 @@
       var _a, _b, key, val;
       return (function() {
         _a = []; _b = this.variables;
-        for (key in _b) { if (__hasProp.call(_b, key)) {
+        for (key in _b) {
+          if (!__hasProp.call(_b, key)) continue;
           val = _b[key];
           val === 'var' ? _a.push(key) : null;
-        }}
+        }
         return _a;
       }).call(this).sort();
     };
     Scope.prototype.assignedVariables = function() {
       var _a, _b, key, val;
       _a = []; _b = this.variables;
-      for (key in _b) { if (__hasProp.call(_b, key)) {
+      for (key in _b) {
+        if (!__hasProp.call(_b, key)) continue;
         val = _b[key];
         val.assigned ? _a.push("" + key + " = " + val.value) : null;
-      }}
+      }
       return _a;
     };
     Scope.prototype.compiledDeclarations = function() {

src/nodes.coffee

@@ -1262,6 +1262,7 @@ exports.ForNode: class ForNode extends BaseNode
     rvar:           scope.freeVariable() unless topLevel
     ivar:           if range then name else if codeInBody then scope.freeVariable() else index or scope.freeVariable()
     varPart:        ''
+    guardPart:      ''
     body:           Expressions.wrap([@body])
     if range
       sourcePart:   source.compileVariables(o)
@@ -1292,14 +1293,11 @@ exports.ForNode: class ForNode extends BaseNode
     else
       varPart:      (namePart or '') and (if @pattern then namePart else "${@idt(1)}$namePart;\n")
     if @object
-      if @raw
       forPart:      "$ivar in $svar"
-      else
-        forPart:    "$ivar in $svar) { if (${utility('hasProp')}.call($svar, $ivar)"
+      guardPart:    "\n${@idt(1)}if (!${utility('hasProp')}.call($svar, $ivar)) continue;" unless @raw
     body:           body.compile(merge(o, {indent: @idt(1), top: true}))
     vars:           if range then name else "$name, $ivar"
-    close:          if @object and not @raw then '}}' else '}'
-    "${sourcePart}for ($forPart) {\n$varPart$body\n$@tab$close$returnResult"
+    "${sourcePart}for ($forPart) {$guardPart\n$varPart$body\n$@tab}$returnResult"
 
 #### IfNode