such as 123;
string such as 'string'; boolean
such as true;
object such as function array;
null such as null;
undefined such as undefined ; obj instanceof Object. The left operand is an object, otherwise it will return false, and the right operand must be a function object or function constructor, otherwise it will return a typeError exception. Instanceof pit: Object type detection between different windows or iframes cannot use instanceof! 3.Object.prototype.toString 4.constructor Any object has a constructor property, inherited from the prototype, the constructor will point to the constructor or constructor that constructs the object. constructor can be overridden, so use it with care.
