小白关于loadsh _.after的问题

Question

官方api的例子写的太简洁
var saves = ['profile', 'settings'];

var done = _.after(saves.length, function() {
console.log('done saving!');
});

_.forEach(saves, function(type) {
asyncSave({ 'type': type, 'complete': done });
});
不是很懂....求大神解释下### 题目描述