JSFiddle - React, Tailwind, and code Playground

by shryme

JavaScript

var arr = [-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 2];

var a = {};

for (var i = 0; i < arr.length; i++) {
    if (arr[i] in a) {
        a[arr[i]] = a[arr[i]] + 1;
    } else {
        a[arr[i]] = 1;
    }
}

var value;
var index;
for (var key in a)
{

    if (a[key] != null && a[key] == 1)
    {
        value = key;
        break;
    }

}
index = arr.indexOf(Number(value));

alert("value: " + value + " index: " + index);