var a=5;
var b=6;
a=a+b;
b=a-b;
a=a-b;
alert(a);
alert(b);

var n=5;
function show(){
  var arr=[];
  return (function(){
    arr.unshift(n);
    n--;
    if(n!=0){
      arguments.callee();
    }
    return arr;
  })();
}
alert(show(n));

var n=5;
var arr=[];
arr.length=n+1;
var arr2=[];
var str=arr.join("a"); //中间连接符用a，要六个数才五个逗号，所以length=n+1
var re=/a/g;
str.replace(re,function(){
  arr2.unshift(n--);
});
alert(arr2);

var n=150;
function show(){
  return Math.min(n,100);
}
alert(show(n));

var n=50;
function show(){
  var arr=[n,100];
  arr.sort();
  return arr[0];
}
alert(show(n));

var n=150;
function show(){
  var str="n";
  for(;str.length<3;){
     return n;
  }
  for(;str.length>=3;){
     return 100;
  }
}
alert(show(n));

var n=50;
function show(){
  var json={};
  var m=n<100||json; //m是布尔值
  for(var attr in m){
    return 100;
  }
  return n;
}
alert(show(n));