sayHi();
 function sayHi(){
     alert("Hi!");
}

 sayHi(); //错误！！函数不存在
 var sayHi=function(){
     alert("Hi!");
}

function factorial(num){
        if (num <= 1){
          return 1;
        } else {
          return num * factorial(num-1);
        }
      }

function factorial(num){
        if (num <= 1){
          return 1;
        } else {
          return num * arguments.callee(num-1);
        }
      }

function createFunctions(){
        var result = new Array();
        
        for (var i=0; i < 10; i++){
          result[i] = function(){
            return i;
          };
        }
        
        return result;
      }
      
      var funcs = createFunctions();
      
      //every function outputs 10
      for (var i=0; i < funcs.length; i++){
        document.write(funcs[i]() + "<br />");
      }

function createFunctions(){
        var result = new Array();
        
        for (var i=0; i < 10; i++){
          result[i] = function(num){
            return function(){
              return num;
            };
          }(i);
        }
        
        return result;
      }

function outputNumbers(count){
        for (var i=0; i < count; i++){
          alert(i);
        }
      
        alert(i);  //count
      }

      outputNumbers(5);

(function(){
 //这里是块级作用域
})();

function outputNumbers(count){
      
        (function () {
          for (var i=0; i < count; i++){
            alert(i);
          }
        })();
        
        alert(i);  //causes an error
      }

function add(num1,num2){
  var sum = num1 + num2;
  return sum; 
}

 function Person(name){

        var a=0;
      
        this.getName = function(){
          return name + a;
        };
      
        this.setName = function (value) {
          name = value;
        };
      }