which of these is more efficient in ColdFusion?
Description:-
isDefined( ) :- Evaluates a string value to determine whether the named variable exists.
structKeyExists( ) :- Determines whether a specific key is present in a structure.
isDefined() workflow:-
This function works like this when we pass a variable name/key in this function it searches this key/name in the below scope table order accordingly.
| Sequence | Scope Name |
| 1 | Local (function-local, UDFs, and CFCs only) |
| 2 | Arguments |
| 3 | Thread local (inside threads only) |
| 4 | Query (not a true scope; variables in query loops) |
| 5 | Thread |
| 6 | Variables |
| 7 | CGI |
| 8 | Cffile |
| 9 | URL |
| 10 | Form |
| 11 | Cookie |
| 12 | Client |
even if we pass the scope name with a variable name/key like this isDefined( "variables.test" ) this will also check in the top scope table order accordingly, and if the variable variables.test key/name is declared in argumentes.test then it will be found in arguments.test variable before variables.test variable.
structKeyExist( ) workflow:-
This function works like this when we pass a variable name/key in this function & also we need to pass the structure/scope in this function as per its arguments method, it only searches this key/name in the specific scope/structure which was passed when it called like structKeyExist( "form", "test" ) or form.keyExist( "test" ). so it will search for fewer scopes.
conclusion:-
by using this structKeyExist( ) function in place of this isDefined( ) the function is far more faster/optimized, it is not only giving some performance but our code is also more readable & maintainable.