JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr;
arr = [
    {id: 4, attr: null},
    {id: 7, attr: null},
    {id: 5, attr: 99},
    {id: 2, attr: 8},
    {id: 9, attr: 3}
];
console.log(testSort(arr));
arr = [
    {id: 7, attr: null},
    {id: 4, attr: null},
    {id: 5, attr: 99},
    {id: 2, attr: 8},
    {id: 9, attr: 3}
];
console.log(testSort(arr));

arr = [
    {id: 5, attr: 99},
    {id: 7, attr: null},
    {id: 2, attr: 8},
    {id: 9, attr: 3},
    {id: 4, attr: null}
];

// sort it here

console.log(testSort(arr));

function testSort(arr) {
    if (arr[0].attr !== null || arr[1].attr !== null) {
        return false;
    }
    if (arr[2].id !== 5 || arr[3].id !== 2 || arr[4].id !== 9) {
        return false;
    }
    return true;
}