Providing Lapsed Time on "Social Network" Post

jsFiddle.

I have created a little javascript snippet that can take two inputs and make a sort of "post" using those. In those posts, it says something like:

Hi!

Posted by Random Person _ minutes ago.

but without the underscore, it should say the lapsed time between now and the time posted. I am having difficulty thinking of how to do this, but this is what I am currently using:

$('#b').click(function () {
    var v = $('#type').val();
    var u = $('#input').val();
    if (v !== "" && u !== "") {
        var time = new Date();
        var currentime = Date.now();
        var x = currentime - time;
        $("ul").prepend("<li>" + v + "<br />Posted by " + u + " " + x + " minutes ago  </li>");
        $('#type, #input').css('border', '');
    } else if (v == "" && u == "") {
        $('#type, #input').css('border', '1px solid red');
    } else if (v == "") {
        $('#type').css('border', '1px solid red');
        $('#input').css('border', '');
    } else {
        $('#input').css('border', '1px solid red');
        $('#type').css('border', '');
    }
});

#type, #input {
    border-radius: 10px;
    background: #dadae3;
    color: #59ACFF;
    border: 1px solid #dadae3;
}
#type {
    border-bottom-right-radius: 0;
}
#type:hover, #input:hover {
    background: #c4c4cc;
    color: #488CCF;
    border: 1px solid #c4c4cc;
}
#type:hover::-webkit-input-placeholder {
    color: #59ACFF
}
#input:hover::-webkit-input-placeholder {
    color: #59ACFF
}
#type:focus, #input:focus {
    border: 1px solid #59ACFF;
    outline: 0;
}
button {
    height: 30px;
    background: #dadae3;
    border-radius: 10px;
    border: 1px solid #dadae3;
    color: #59ACFF;
    cursor: pointer;
}
button:hover {
    background: #c4c4cc;
    color: #488CCF;
    border: 1px solid #c4c4cc;
}
button:focus {
    outline: 0;
}

<script src="http://ift.tt/Zv5K7g"></script>
<link href="http://ift.tt/1FHelXo" rel="stylesheet"/>
<link href="http://ift.tt/18QXBAt" rel="stylesheet"/>
<br />
<textarea id='type'></textarea>
<br />
<br />
<input id='input'>
<br />
<br />
<button id='b'><span class='fa fa-plus-square-o fa-2x'></span>

</button>
<ul id='ul'></ul>

I realize that this is wrong, but I cannot think of other ways to do this.

Thank you. :)