find array from an index code example

Example 1: index of value in array

// for dictionary case use findIndex 
var imageList = [
   {value: 100},
   {value: 200},
   {value: 300},
   {value: 400},
   {value: 500}
];
var index = imageList.findIndex(img => img.value === 200);

Example 2: js array get index

var fruits = ["Banana", "Orange", "Apple", "Mango"];
return fruits.indexOf("Apple"); // Returns 2