can someone help me with this please

https://w.trhou.se/3uzr2xf6m5

if you go to the student.js and go to the for loop towards the bottom, ok so i get how all the code runs and everything, but what im confused with is after it loops through students, it stores the loop information into student variable, but then for the IF statement, how does the script know what name to match it too? Like i get if i type in Dave the IF statement is true and continues to run the 2 functions, but in the studentreport function, how does it know which index value to get from? Once the IF statement is true, is what was entered into user, is that index value passed to the studentreport function? because i thought the code in the if statement is just to determine if true than whats in the bracket is the code that runs. I'm so confused here,

thanks for any help sorry if its a hard to understand question, I don't understand it to well so its kinda hard to explain what I mean