Edit in JSFiddle

var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// the lodash way 
cool = _.pluck(users, 'user');

// Pure JS
notCool = [];
users.forEach(function(entry) {
    notCool.push(entry['user']);
});

//display it on page
document.getElementById("cool").innerHTML = JSON.stringify(cool);
document.getElementById("not-cool").innerHTML = JSON.stringify(notCool);
Lodash result:
<p id="cool"></p>
Pure JS result:
<p id="not-cool"></p>
body {
    font-family: sans-serif;
}
p {
    border-bottom: 1px solid black;
    padding: 15px;
}

#cool {
    background: rgba(0, 255, 0, 0.2);
}

#not-cool {
    background: rgba(255, 0, 0, 0.2);
}
}

External resources loaded into this fiddle: