javascript - “！-”在JavaScript中有什么作用？(What does “!--” do in JavaScript?)

Question

I have this piece of code (taken from this question ):

(我有这段代码（取自这个问题 ）：)

var walk = function(dir, done) {
    var results = [];

    fs.readdir(dir, function(err, list) {
        if (err)
            return done(err);

        var pending = list.length;

        if (!pending) 
            return done(null, results);

        list.forEach(function(file) {
            file = path.resolve(dir, file);
            fs.stat(file, function(err, stat) {
                if (stat && stat.isDirectory()) {
                    walk(file, function(err, res) {
                        results = results.concat(res);

                        if (!--pending)
                            done(null, results);
                    });
                } else {
                    results.push(file);

                    if (!--pending) 
                        done(null, results);
                }
            });
        });
    });
};

I'm trying to follow it, and I think I understand everything except for near the end where it says !--pending .

(我正在尝试遵循它，我想我了解所有内容，除了它说的末尾!--pending)

In this context, what does that command do?

(在这种情况下，该命令有什么作用？)

Edit: I appreciate all the further comments, but the question has been answered many times.

(编辑：我感谢所有进一步的评论，但问题已得到解答很多次。)

Thanks anyway!

(不管怎么说，还是要谢谢你！)

  ask by Kieran E translate from so