勿乱动arguments对象

1: function chrome_bug(a, b) {   2:        arguments[1] = 2;   3:        alert(b); // Chrome:2, other:undefined   4: }   5:     6: chrome_bug(1);

1: <script type='text/javascript'>   2:     ~function(a){   3:         var a= 'false';   4:         alert(arguments[0]);//都输出'false'   5:     }(true);   6: </script>

1: <script type='text/javascript'>   2:     ~function(a){   3:         Array.prototype.splice.call(arguments,0,1);   4:         alert(a);//chrome为'undefined' 其它浏览器为 1   5:     }(1);   6: </script>

1: <script type='text/javascript'>   2:     ~function(a, b) {   3:         arguments[1] = 2;   4:         alert(b);//chrome为2 其它浏览器为'undefined'   5:     }(1);   6: </script>

1: <script type='text/javascript'>   2:     ~function(a, b) {   3:         arguments[1] = 2;   4:         b = 3;   5:         alert(arguments[1]);//chrome为3 其它浏览器为2   6:     }(1);   7: </script>

1: // Copyright 2006-2008 the V8 project authors. All rights reserved.   2: // Redistribution and use in source and binary forms, with or without   3: // modification, are permitted provided that the following conditions are   4: // met:   5: //   6: //     * Redistributions of source code must retain the above copyright   7: //       notice, this list of conditions and the following disclaimer.   8: //     * Redistributions in binary form must reproduce the above   9: //       copyright notice, this list of conditions and the following  10: //       disclaimer in the documentation and/or other materials provided  11: //       with the distribution.  12: //     * Neither the name of Google Inc. nor the names of its  13: //       contributors may be used to endorse or promote products derived  14: //       from this software without specific prior written permission.  15: //  16: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS  17: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT  18: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR  19: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT  20: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,  21: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT  22: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,  23: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY  24: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT  25: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE  26: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  27:    28: #ifndef V8_ARGUMENTS_H_  29: #define V8_ARGUMENTS_H_  30:    31: namespace v8 {  32: namespace internal {  33:    34: // Arguments provides access to runtime call parameters.  35: //  36: // It uses the fact that the instance fields of Arguments  37: // (length_, arguments_) are "overlayed" with the parameters  38: // (no. of parameters, and the parameter pointer) passed so  39: // that inside the C++ function, the parameters passed can  40: // be accessed conveniently:  41: //  42: //   Object* Runtime_function(Arguments args) {  43: //     ... use args[i] here ...  44: //   }  45:    46: class Arguments BASE_EMBEDDED {  47:  public:  48:   Arguments(int length, Object** arguments)  49:       : length_(length), arguments_(arguments) { }  50:    51:   Object*& operator[] (int index) {  52:     ASSERT(0 <= index && index < length_);  53:     return arguments_[-index];  54:   }  55:    56:   template <class S> Handle<S> at(int index) {  57:     Object** value = &((*this)[index]);  58:     // This cast checks that the object we're accessing does indeed have the  59:     // expected type.  60:     S::cast(*value);  61:     return Handle<S>(reinterpret_cast<S**>(value));  62:   }  63:    64:   // Get the total number of arguments including the receiver.  65:   int length() const { return length_; }  66:    67:   Object** arguments() { return arguments_; }  68:    69:  private:  70:   int length_;  71:   Object** arguments_;  72: };  73:    74:    75: // Cursom arguments replicate a small segment of stack that can be  76: // accessed through an Arguments object the same way the actual stack  77: // can.  78: class CustomArguments : public Relocatable {  79:  public:  80:   inline CustomArguments(Object* data,  81:                          JSObject* self,  82:                          JSObject* holder) {  83:     values_[3] = self;  84:     values_[2] = holder;  85:     values_[1] = Smi::FromInt(0);  86:     values_[0] = data;  87:   }  88:   void IterateInstance(ObjectVisitor* v);  89:   Object** end() { return values_ + 3; }  90:  private:  91:   Object* values_[4];  92: };  93:    94:    95: } }  // namespace v8::internal  96:    97: #endif  // V8_ARGUMENTS_H_