// Durations are in minutes 
const tasks = [
  {
    'name'     : 'Write for Envato Tuts+',
    'duration' : 120
  },
  {
    'name'     : 'Work out',
    'duration' : 60
  },
  {
    'name'     : 'Procrastinate on Duolingo',
    'duration' : 240
  }
];

const task_names = [];
 
for (let i = 0, max = tasks.length; i < max; i += 1) {
    task_names.push(tasks[i].name);
}

console.log(task_names) // [ 'Write for Envato Tuts+', 'Work out', 'Procrastinate on Duolingo' ]