Description
Evaluates a string value to determine whether the variable named in it exists. This function is an alternative to the ParameterExists function, which is deprecated.
Returns
True, if the variable is found; False, otherwise.
Category
Syntax
IsDefined(variable)
See also
History
ColdFusion (2018 release): Introduced named parameters.
ColdFusion MX: Changed behavior: this function can process only the following constructs:
- A simple variable
- A named variable with dot notation
- A named structure with dot notation (for example: mystruct.key)
Parameters
Parameter |
Description |
|---|---|
variable |
String, enclosed in quotation marks. Name of variable to test for. |
Usage
Passing an array entry, such as myArray3 to this function causes an error. To check whether a specific entry exists in an array, use the ArrayIsDefined function.You can test whether a specific key exists in a structure by using this function or the StructKeyExists function. For example, when working with scopes that ColdFusion exposes as structures, the StructKeyExists function can sometimes replace this function. The following lines are equivalent:
if(isDefined("form.myVariable"))
if(structKeyExists(form,"myVariable"))
Example
<cfscript>
myarray=["1","4","23","5","54"];
for(i=1; i <= arrayLen(myarray); i++){
writeoutput(myarray[i] & "<br>");
}
writeOutput(isDefined("myarray"))
</cfscript>
Output
1
4
23
5
54
YES
Sign in to your account