JavaScript function for variable type

You need to write a bit about this function. Code . The following function can get a variable type. When you call a variable, a variable type described in the string format will be returned. Copy code The Code is as follows: // obtain the type of x and return the type name.
Function GetType (x ){
// If X is null, null is returned.
If (x = NULL) Return "null ";
VaR T = typeof X;
// If X is a simple type, the return type name
If (T. tolocalelowercase ()! = "Object") return T;
// Call the tostring method of the object class to obtain the type information.
// The object. tostring method returns information similar to this [object class name]
T = object. Prototype. tostring. Apply (x). tolowercase ();
// Intercept the class name part returned by the tostring Method
T = T. substring (8, T. Length-1 );
If (T. tolocalelowercase ()! = "Object") return T;
// Check whether X is of the Object Type
If (X. constructor = Object) return T;
// Obtain the type name from the constructor
If (typeof X. constructor = "function ")
Return getfunctionname (X. constructor );
Return "unknow type ";
}
// Obtain the function name
Function getfunctionname (FN ){
If (typeof FN! = "Function") throw "the argument must be a function .";
VaR Reg =/\ W * function \ s + ([\ W \ $] +) \ s *\(/;
VaR name = reg.exe C (FN );
If (! Name ){
Return '(anonymous )';
}
Return name [1];
}