Everyone knows about Javascript
TypeofThe types of variables can be obtained, but there are only six return values for typeof: "number," "string," "Boolean," "object," "function," and "undefined ."
In fact, JavaScript still has many special categories, such as array and date. Why can't they be returned in typeof?
Originally, JavaScript classifies array date objects as object classes.InstanceofTo determine the exact category of the object.
Here is a simple example to illustrateInstanceofUsage
Program code
FunctionObjtest (OBJ ){
VaRI, T, S = ""; // create a variable.
T =
New
Array(); // Create an array.
T ["date"] =
Date; // Fill in the array.
T ["object"] =
Object;
T ["array"] =
Array;
For(I
InT)
{
If(OBJ instanceof T [I]) // check the OBJ class.
{
S + = "obj is an instance of" + I + "\ n ";
}
Else
{
S + = "obj is not an instance of" + I + "\ n ";
}
}
Return(S); // returns a string.
}
VaROBJ =New Date();
Response. Write (objtest (OBJ ));
(From pjhome)
