Coursera GMscript for time left

coursera_time_left.js

// ==UserScript==
// @name        Show time remaining
// @namespace   Yanick
// @description Show the tiem of videos remaining
// @include     https://class.coursera.org/proglang-003/*
// @require       http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js
// @version     1
// @grant       none
// ==/UserScript==

function updateLeftover() {
$('div.course-item-list-header').each(function(){
    if( $(this).find('h3 .remainder' ).length === 0 ) {
        $(this).children('h3')
            .append('<span class="remainder" style="font-size: small">'
                + ' -- ' + '<span class="r"></span> mins left</span>');
    }

    var time_left = $(this).next().children('li.unviewed').map(function(){
        var r = $(this).text().match(/\((\d+):(\d+)\)/);
        return r ? 60 * parseInt(r[1]) + parseInt(r[2]) : 0;
    }
    ).get().reduce(function(x,a){ return x + a },0);

    if ( time_left > 0 ) {
        $(this).find('h3 .remainder').show();
        $(this).find('h3 .remainder .r').text(
            parseInt(time_left / 60)
        );
    }
    else {
        $(this).find('h3 .remainder').hide();
    }

});
}

updateLeftover();
var t = setInterval(updateLeftover, 60000);