javascript中隐藏了hashcode，提供了toString方法

//The instanceof Operator
//检测 某个对象是否由某个构造构造出来
var date=new Date();
date instanceof Date;
date instanceof Object;
date instanceof Number;

 

//javascript中隐藏了hashcode，提供了toString方法 var user = { name:"zhangsan", age:22, toString:function(){ return this.name; } } if(user=="zhangsan"){ alert("aaa"); }

 

//The in operator
var point = { x:1,y:1};

//&& || ！
var i=1;
var y = 2;
if(!(y instanceof String) && y>i){
   alert("hello");
}

 

//&& &
var x=5;
if(x++==2 & x++==3){
}


if(x++==2 && x++==3){

}
alert(x);

 

var has_x_coord="x" in point; var has_z_coord="z" in point; alert(has_x_coord); alert(has_z_coord);

 

//The instanceof Operator
//检测 某个对象是否由某个构造构造出来
var date=new Date();
date instanceof Date;

//The instanceof Operator
//检测 某个对象是否由某个构造构造出来
var x={};
x[0]=99;
x[1]=98;
x[3]=77;

x.length=3;
if(x instanceof Array){
   alert("Array");
}else{
  alert("Object");
}

 

 

//&& &
var x=5;
if(++x==2 & ++x==3){
}


if(++x==2 && ++x==3){

}
alert(x);

 

//求二进制数
var x=2;
var str="";
while(x>=1){
  var q=x%2;
   x=parseInt(x/2);
   str=q+str;
}
alert(str);