Returns a Boolean value that indicates whether or not an object is an instance of a particular class.

result = object instanceof class

Arguments

result

Required. Any variable.

object

Required. Any object expression.

class

Required. Any defined object class.

Remarks

The instanceof operator returns true if object is an instance of class. It returns false if object is not an instance of the specified class, or if object is null.

Example

The following example illustrates the use of the instanceof operator.

function objTest(obj){
   var i, t, s = "";   // Create variables.
   t = new Array();   // Create an array.
   t["Date"] = Date;   // Populate the array.
   t["Object"] = Object;
   t["Array"] = Array;
      for (i in t)
      {
         if (obj instanceof t[i])   // Check class of obj.
         {
            s += "obj is an instance of " + i + "\n";
         }
         else 
         {
            s += "obj is not an instance of " + i + "\n";
         }
   }
   return(s);   // Return string.
}

var obj = new Date();
response.write(objTest(obj));

Requirements

Version 5

See Also

Operator Precedence | Operator Summary