[js]面向对象2

删除对象的属性

删除未用var定义的变量.

• delete返回布尔
• 删除不存在的属性,返回true
• 无法删除原形中的属性 如 delete obj.toString()

resu=delete obj.name;
# resu返回值是true

var num1=100;
console.log(num1);
console.log(window.num1);
# 100 100

num1=100;
console.log(num1);
console.log(window.num1);
# 100 100

var num1=100;
delete(num1); 
console.log(window.num1);
# 100

num1=100; //未使用var,可被delete删除
delete(num1); 
console.log(window.num1);
## undefined