Lookup string in Array

This is going to be a 2 part question. Overall goal is to write a script that will add the selected values of a multi-select field on a transaction record to an array, use If statements to look for a string in the array and when found call an email function to email a specific recipient. I'm having issues with the string lookup and calling the email function and continuing the iteration through the array.

Part 1) How to lookup a specific string in an array? What I have below uses the concept of if (array == "String") { do something. The issue here is if there is more than one value in the array, the if statement is satisfied and the loop seems to exit.