Question

app.use(function(req, res, next) {
    var chatlog = [];
    console.log('executed many timews why?')   
 var chatlog = redisClient.lrange('messages', 0, 99, function(err, reply) {
        if (!err) {
            var result = [];
            for (var msg in reply) result.push(JSON.parse(reply[msg]));
            if (result.length == 0) { 
                result.push({
                    "msg": 'welcome',
                    "nickname": "guest1"
                })
            }
            console.log(result)
        } else {
            console.log('error getting chat messages')
        }
        res.locals = {
            chatlog: result
        };
        next();
        return
    });

  app.get('/', (req, res) => {
 res.render('index', {     })
  })

当我访问'/'一次时，控制台会打印以下内容：

executed many timews why
[ { msg: 'welcome', nickname: 'guest1' } ]
executed many timews why
executed many timews why
executed many timews why
executed many timews why
[ { msg: 'welcome', nickname: 'guest1' } ]
[ { msg: 'welcome', nickname: 'guest1' } ]
[ { msg: 'welcome', nickname: 'guest1' } ]
[ { msg: 'welcome', nickname: 'guest1' } ]
executed many timews why
executed many timews why
[ { msg: 'welcome', nickname: 'guest1' } ]
[ { msg: 'welcome', nickname: 'guest1' } ]
executed many timews why
[ { msg: 'welcome', nickname: 'guest1' } ]

如何让我的中间件只执行一次？如果我接下来拿走它，它只运行一次但页面不会加载，如果我保持next（），它会执行多次。

Answer 1

您的中间件已设置为每个请求都会被调用。这意味着，如果配置不正确的Express，将为您在索引模板中使用的每个图像，样式表或JS文件调用它。

如果这些文件由express.static提供，请确保在 express.static声明之后加载中间件：

app.use(express.static(...)); app.use(...your middleware...); app.get('/', ...);

这样，您的中间件就不会被调用静态资源，因为express.static会在您的中间件之前处理它们。

您还可以创建单独的中间件功能并将其插入特定路径：

let myMiddleware = function(req, res, next) { ... }); app.get('/', myMiddleware, function(req, res) { res.render('index', {}) });

快速中间件被多次调用

1 个答案: