返回由调用者传递给一个函数的实际参数数目。

[function.]arguments.length

function

可选项。当前正在执行的 Function 对象的名称。

对象的 length 属性被脚本引擎初始化为该函数中开始执行时，传递给 Function 对象的实际参数数目。

下面的示例阐释了 arguments 对象的 length 属性的用法。

function argTest(a, b) : String {
   var i : int;
   var s : String = "The argTest function expected ";
   var numargs : int = arguments.length; // Get number of arguments passed.
   var expargs : int = argTest.length;   // Get number of arguments expected.
   if (expargs < 2)
      s += expargs + " argument. ";
   else
      s += expargs + " arguments. ";
   if (numargs < 2)
      s += numargs + " was passed.";
   else
      s += numargs + " were passed.";
   s += "\n"
   for (i =0 ; i < numargs; i++){        // Get argument contents.
      s += "  Arg " + i + " = " + arguments[i] + "\n";
   }
   return(s);                            // Return list of arguments.
}
print(argTest(42));
print(argTest(new Date(1999,8,7),"Sam",Math.PI));

当使用 /fast- 选项编译后，该程序的输出为：

The argTest function expected 2 arguments. 1 was passed.
  Arg 0 = 42
The argTest function expected 2 arguments. 3 were passed.
  Arg 0 = Tue Sep 7 00:00:00 PDT 1999
  Arg 1 = Sam
  Arg 2 = 3.141592653589793

版本 5.5

参考