1 .直接查找属性,判断未定义
var str={fname:'uw3c ',lname:'js ',age :10 } console.log (str.fname ); //u W3C控制台. log (str.sex ); 使用//undefined2.in运算符确定是true还是false
var str={fname:'uw3c ',lname:'js ',age :10 } console.log (fname ' instr ); //trueconsole.log(sex'instr ); //false 3.删除指定的属性
var str={fname:'uw3c ',lname:'js ',age:10}delete str.fname; 删除fname属性delete str.age; //删除age属性console.log(str )//输出{lname:'js'}
参考: http://www.uw3c.com/js views/js23.html