How To get Value in AJAX JSON FROM PHP

Question

PHP ajax code:

$.ajax({
    type    : "POST",
    data    : dataString,
    url     : "php_proceess_file",
    dataType: "json",
    success : function (JSONObject) {
        var peopleHTML = "";            
        var i = 0;            
        for (var key in JSONObject) {
            if (JSONObject.hasOwnProperty(key)) {           
                pm = JSONObject[key]["pm"];
            }
        }
    }   
});

PHP process file:

$pm = unserialize($item_row['payment_modes']);    
    array_push($someArray, [    
        'pm' => $pm,    
    ]);
}

// Convert the Array to a JSON String and echo it
$someJSON = json_encode($someArray);
echo $someJSON;

I want this type of result single one by one like, how to get nested json value?

If (2710000001 != ''){
    Echo 'result'
}

Please check image: