var myArray = [
"J20J205147902_B_B716202",
"R20Q205147902_F_B716202",
"P20W205147_902_alternate1",
"M20K205147_902_alternate4",
"F20G205147_902_alternate3",
"K20J205147_902_alternate2",
"L20H205147_902_main"];

var map = {
"_F_":1,
"_main":2,
"_alternate1":3,
"_alternate2":4,
"_alternate3":5,
"_alternate4":6,
"_alternate5":7,
"_B_":8