1、刪除沒有使用var定義的變量
var name = "qwe";
age = 21;
delete name;
delete age;
console.log(age);//age is undefined
console.log(name);//qwe
2、刪除對象的屬性
var obj = {"name":"wxm","age":21};
delete obj.name;
console.log(obj.name);-----name is undefined
3、返回值
屬性可以刪除,則返回true,否則返回false;使用delete不能刪除在函數內部聲明的變量,不能刪除全局變量中使用var聲明的變量