js对象属性特性（可写，枚举，可配置）

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title></title>
    </head>
    <body>
<script type="text/javascript">
var obj={};
//obj.x=1;
//obj.y=2;
//obj.x=123;
//obj.y=4566;
//console.log(obj.x+'\n'+obj.y);
//for(var p in obj){
//    console.log(p);
//}
//console.log(Object.keys(obj));
//console.log(Object.getOwnPropertyNames(obj));
Object.defineProperty(obj,'x',{
    value:12
});
//console.log(obj.x);
//obj.x=456;
//console.log(obj.x);
//for(p in obj){
//    console.log('对象中得属性：'+p+'\n');
//}
//console.log(Object.keys(obj));
//console.log(Object.getOwnPropertyNames(obj));
Object.defineProperty(obj,'y',{
    value:56,
    writable:true,//代表是否可写
    enumerable:true,//是否可枚举
    configurable:false//是否可配置
});
//console.log(obj.y);
//obj.y=777;
//console.log(obj.y);
//for(p in obj){
//    console.log(p);
//}
console.log(Object.keys(obj));
//console.log(Object.getOwnPropertyNames(obj));
Object.defineProperty(obj,'z',{
    value:'this is a test',
    writable:true,
    enumerable:true,
    configurable:true
});
console.log(obj.z);
obj.z='hello';
console.log(obj.z);
delete obj.z;
console.log(obj.z);
Object.defineProperty(obj,'k',{
    value:1,
    writable:false,//可写
    enumerable:false,//可枚举
    configurable:true//可配置
});
console.log(obj.k);
obj.k=3;
console.log(obj.k);
Object.defineProperty(obj,'k',{
    writable:true,
    enumerable:true
});

obj.k=5;
console.log(obj.k);
console.log(obj.propertyIsEnumerable('k'));
















































</script>
    </body>
</html>

posted @ 2018-03-01 16:10  郭帅  阅读(390)  评论(0)    收藏  举报