Returns a clone, also known as a deep copy, of a variable. There is no reference to the original variable.


A clone of a variable.


Structure functionsSystem functions

Function syntax


See also

StructCopy, other Structure functionsModifying a ColdFusion XML object in the Developing ColdFusion Applications


ColdFusion (2018 release): Introduced named parameters.

ColdFusion 8: Changed behavior: this function can duplicate CFCs.

ColdFusion MX: Changed behavior: this function can be used on XML objects.





Name of a variable to duplicate


Use this function to duplicate complex structures, such as nested structures and queries.When you duplicate a CFC instance, the entire CFC contents is copied, including the values of the variables in the this scope at the time you call the Duplicate function. Thereafter, the two CFC instances are independent, and changes to one copy, for example by calling one of its functions, have no effect on the other copy.

Note: With this function, you cannot duplicate a COM, CORBA, or JAVA object returned from the cfobject tag or the CreateObject function. If an array element or structure field is a COM, CORBA, or JAVA object, you cannot duplicate the array or structure.


    s1 = StructNew()
    s1.nested = StructNew()
    s1.nested.item = "original"
    copy = StructCopy(s1)
    clone = Duplicate(s1)
    // modify the original struct
    s1.nested.item = "modified"
    writeOutput("The copy contains the modified value: " & copy.nested.item & "<br/>")
    writeOutput("The duplicate contains the original value: " & clone.nested.item)