Loop through models and check if an attribute exists

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
<table class="js-output"></table>

<script type="text/html" id="tmpl">
    <tr>
        
<td>
    <% _.each(data.mappedSessions, function(session) {
        var deleteSessionAvailable =  _.indexOf(data.deleteSessions, session) >= 0;
        var gfidSelectedOption =  _.where(data.sessionMapping, session);

                console.log(session, gfidSelectedOption[session]);
    %>
                <li class="td-options__item <% if(data.availableSessions === 0) { %>is-hidden<% } %>">
                    <select name="" class="td-options__select js-sessions-select" data-sessionid="<%= session %>" <% if(deleteSessionAvailable) { %> disabled <% } %>>
                        <option></option>

                        <% _.each(availableIds, function(item) { %>
                            
                            <!-- if gfidSelectionOptions[session] === session then add 'selected' to option ???? -->
                            <option value="<%= item.id %>"><%= item.id %> &ndash; <%= item.name %> &ndash; (<%= data.availableSessions %> Available)</option>
                        <% }) %>
                            </select>                   
                </li>
            <% }) %>
</script>
                                </td>
                                    </tr>

JavaScript

console.clear();

var availableIds = [
	{
		"id": "5Q6",
		"name": "Campo 2"
	},
	{
		"id": "7GH",
		"name": "Camposinos"
	},
	{
		"id": "8X6",
		"name": "Rangers"
	}
];

var data = {
	"id": "6H6",
	"name": "Joes Shack",
	"mappedSessions": [
		"X0101",
		"B1800",
		"B1888",
		"F3005"
	],
	"sessionAllowance": 5,
	"availableSessions": 1,
	"selectable": true,
	"selected": true,
	"deleteSessions": [],
	"sessionMapping": {
		"X0101": {
			"id": "5Q6",
			"name": "MATOUR TRADING LLC"
		},
		"B1800": {
			"id": "7GH",
			"name": "PATOUR TRADING LLC"
		}
	}
}

var template = _.template($('#tmpl').html());

$('.js-output').html(template({
    data: data,
    availableIds: availableIds
}));


//_.each(data.mappedSessions, function(session) {
//    var gfidSelectedOption =  _.where(data.sessionMapping, session);
//    console.log(gfidSelectedOption);
//});