js六种数据类型:Sting Object undefined Array Boolean Number
js五种基本类型:String Boolean Number null undefined
typeof六种返回格式:’string’ ‘number’ ‘object’ ‘function’ ‘boolean’ ‘undefined’
typeof null; // “object”(可以理解为检测空对象指针,那就是“对象”咯)
js六种数据类型:Sting Object undefined Array Boolean Number
js五种基本类型:String Boolean Number null undefined
typeof六种返回格式:’string’ ‘number’ ‘object’ ‘function’ ‘boolean’ ‘undefined’
typeof null; // “object”(可以理解为检测空对象指针,那就是“对象”咯)