Whenever I use a for ... in loop, the index variable of the loop always seems to be in the variables scope.
For example if I have a component with a method that uses this loop:

for(key in params){  
    writeOutput(key);  
}

The variable 'key' will be placed in the variables scope. If I already have declared a variables.key anywhere in the component, this value gets overwritten when I use this for ... in loop. What I actually need is something like this:

for(var key in params){
    writeOutput(key);
}

This however throws a parsing error.

Is there any way to put the for ... in index in a different scope then the variables scope?

• coldfusion
• scope
• for-in-loop

The default scope inside CFCs is variables if you don't var beforehand.

You have to var the index outside the loop like so:-

var key = "";

for(key in params){
    writeOutput(key);
}

An alternative approach, to avoid varring everything within your functions, is to declare your variables within a "local" structure. In CF9 a local scope is built in but for CF8 or below do something like this:-

var local = structNew();

for(local.key in params){
  writeOutput(local.key);
}

This syntax will work in ColdFusion 9 and higher:

for ( var key in params ){
    writeOutput( key );
}