//JavaScript函数//简单的求和函数
function sum(a,b)
{return a + b;
}//函数可以存储在变量中，也可以通过变量调用函数
x = sum(a,b);
x(1,2);//自调用函数
(function(){var x = "Hello"; //以上函数实际上是一个 匿名自我调用的函数 (没有函数名)。
})//arguments.length 属性返回函数调用过程接收到的参数个数：
function MyFunction(a,b,c,d)
{return arguments.length;
}
document.getElementById("demo").innerHTML = MyFunction(1,2,3,4)function myFunction(a,b){if (a === undefined){a = 0;}else{a = b;}
}//Arguments 对象
x = FindMax(1,2336,99,23135,43,13,-56)
function FindMax(){var i,max = 0;for(i  = 0;i< arguments.length;i++){if(arguments[i] > max){max = arguments[i];}}return max;
}
document.getElementById("demo").innerHTML = FindMax(1,2,3,4,56,8,965,54);//定义一个求和函数
y = get_sum(1,2336,99,23135,43,13,-56)
function get_sum(){var i,sum = 0;for (i = 0;i<arguments.length;i++){sum += arguments[i];}return sum;
}
document.getElementById("demo").innerHTML = FindMax(1,2,3,4,56,8,965,54);//window.myFunction()//函数作为方法调用
var myObject = {firstname:"Jone",lastName:"Done",fullName: function(){return firstName + " "+lastName;}
}
//调用函数
var obj = myObject.fullName();//构造函数
function myFunction(arg1,qrg2){this.firstName = arg1;this.lastName = arg2;
}
//构造实例
var x = new myFunction("Jone","Steve");
x.firstName;
x.lastName;function get_Div(a,b){return a*b;
}
get_Div.call(get_Div,10,2);//return 20function myFunction(a, b) {return a * b;
}
myArray = [10,2];
myFunction.apply(myObject, myArray);   // 返回 20//计数器
function add(){counter = 0;function plus(){counter ++;}plus();return counter;
}