1, in运算符
2, hasOwnProperty()
3, != undefined
//检测o对象里是否有属性a
var o={a:1,b:2,c:3};
console.log("a" in o);
console.log(o.hasOwnProperty("a"));
console.log(o.a != undefined);
时间: 2024-07-31 11:19:18
1, in运算符
2, hasOwnProperty()
3, != undefined
//检测o对象里是否有属性a
var o={a:1,b:2,c:3};
console.log("a" in o);
console.log(o.hasOwnProperty("a"));
console.log(o.a != undefined);