instanceof Operator (Windows Scripting - JScript)

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

Syntax

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.

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();
document.write(objTest(obj));

Requirements

Version 5

Change History

See Also

Operator Precedence (Windows Scripting - JScript)
Operator Summary (Windows Scripting - JScript)