PS Scripts : Javascripting and functions

[bungdaddy]

I am new to PS scripting and trying to create a basic script to gather folder paths and then remove the path of that folder. I have created a basic array and while trying to

var v = labs[i].substring(labs[i].lastIndexOf("/")+1);

ESTK throws an error that "labs.substring is not a function." This seems to be valid javascript, does ESTK require a different syntax or something?

Thanks

#target photoshop
//Sizes Tab
//Lab Drop-down menu
var labSets = Folder('~/Desktop/Template Hub/');
var labSets = labSets.getFiles();


//Create Array containing Lab names from folder names
var labs = labSets;
for (i=0; i<labs.length; i++) {
    var v = labs[i].substring(labs[i].lastIndexOf("/")+1);
  
}