Dynamically assigning StackName to a Lambda function in AWS

I have created a stack with the necessary outputs from the Root template to connect them to another separate stack using a lambda function which gets the Network(root)StackName. All of our stack names start with 'new-' so I want to use the Lambda function to search for this subsidiary.

I have modified my Lambda function as follows;

var getName = event.ResourceProperties.StackName;
var stackName = (getName.slice(0, 2) == "new/"); 

However all that has done has made it look for a stack called "new". Is there a way in JavaScript of adding a wildcard at the end so it finds the rest of the stack name?