Yes, you can use substrings and I think it's the same syntax... For finding a word in a file, I would use something like
code:
var myString = TextFromFile //contains text from file
myString = myString.split(" ");
for(var i=0;i<=myString.length;i++){
if(myString[i]==KeyWord){
//Code
}
}
There is probably an easier, more correct way to do this though