hows to write function for array in javascript code example

Example 1: javascript declare array

var array = []

Example 2: javascript get array value

var array = []
array[0] = "hi"
array[1] = "dude"
var done = false
while (done == false){
var valueToFind = "hi";
  var rounds = array.length;
  if (rounds < 0){
  return false
  }
  if (array[rounds] == valueToFind){
  done = true
    return rounds
  }
  rounds = rounds - 1
}