Edit in JSFiddle

var ladies = [
    { name: 'Maria', maritalStatus: 'single' },
    { name: 'Jane', maritalStatus: 'single' },
    { name: 'Lucy', maritalStatus: 'single' },
    { name: 'Anne', maritalStatus: 'single' }
];

var ladiesAreSingle = _.all(ladies, function (lady) {
    return lady.maritalStatus === 'single';
});

if (ladiesAreSingle) {
    alert('If you liked it then you shoulda put a ring on it.');
}