Using Optional Chaining for checking for existence of nested Object key

Using Optional Chaining for checking for existence of nested Object key

In PHP we can do use isset() for checking the existence of a deeply nested array's key since the beginning of time :

<?php
$p1 = "a9bedbd81019b877";
$p2 = "47bd5f64f7be5578";

$obj =
[
    'people' =>
    [
        $p1 =>
        [
            'first_name' => 'John',
            'last_name' => 'Smith',
            'suffix' => 'Sr',
            'results' => [ 'math' => 82, 'english' => 79, 'science' => 50 ]
        ],

        $p2 =>
        [
            'first_name' => 'Timothy',
            'middle_name' => 'Bob',
            'last_name' => 'Jones'
        ]
    ]
];

if (isset($obj['people'][$p1]['results']['science']))
{
    echo $obj['people'][$p1]['results']['science'];
}
echo "\n";
if (!isset($obj['people'][$p2]['results']['science']))
{
    echo 'Not Found';
}
echo "\n";
?>

There are many solutions to this in JavaScript like the answers given here in StackOverflow.

But I think the best solution lies in ECMA 262 (ES2020) which now all browsers support.

let p1 = "a9bedbd81019b877";
let p2 = "47bd5f64f7be5578";

let obj =
{
    'people' :
    {
        [p1] :
        {
            'first_name': 'John',
            'last_name': 'Smith',
            'suffix': 'Sr',
            'results': { 'math': 82, 'english': 79, 'science': 50 }
        },

        [p2] :
        {
            'first_name': 'Timothy',
            'middle_name': 'Bob',
            'last_name': 'Jones',
        }
    }
}

if (obj?.people?.[p1]?.results?.science)
{
    console.log('science = ', obj?.people?.[p1]?.results?.science);
}

console.log(obj?.people?.[p2]?.results?.science);

Output :

science =  50
undefined