JSFiddle - React, Tailwind, and code Playground

JavaScript

var array1 = ["50","51","52","53","54","55","56","57","58","59"];
var array2 = ["59","55","51"];
var stored_index = array2.map(function(val){
    return array1.indexOf(val)
}).filter(function(val){
    return (val != -1)
});

console.log(stored_index)//output [9, 5, 1]