javascript - NodeJS - 如何打破一个功能？

Question

最近有一个类似的问题，但仍然无法解决。在添加新用户之前，我必须验证注册页面。

app.post('/signup', function(req, res) {
    //checking if first name is filled
    if (req.body.first_name = "" || req.body.first_name = null || req.body.first_name = undefined) {
      res.render('signup', { "title": "Ttitle", "menu": "signup", user: req.user, "error" : "empty_first_name" });
      break;
    }
    //checking if last name is filled
    if (req.body.last_name = "" || req.body.last_name = null || req.body.last_name = undefined) {
      res.render('signup', { "title": "Ttitle", "menu": "signup", user: req.user, "error" : "empty_last_name" });
      break;
    }
    //checking if email is filled
    if (req.body.email = "" || req.body.email = null || req.body.email = undefined) {
      res.render('signup', { "title": "Ttitle", "menu": "signup", user: req.user, "error" : "empty_email" });
      break;
    }
    //checking if passwords match
    if (req.body.password != req.body.repassword) {
      res.render('signup', { "title": "Ttitle", "menu": "signup", user: req.user, "error" : "pass_missmatch" });
      break;
    }
    ...
    ...
    ...
    //and finally if everything seems to be OK...
    addUser(req.body.email, req.body.password, req.body.first_name, req.body.last_name, req.body.country, function(status) {
        res.render('signup', { "title": "Ttitle", "menu": "signup", user: req.user, "success" : 1 });
    });
});

Node.JS 告诉我所有的中断都是非法的。但是我应该如何以适当的方式破坏我的功能呢？它不返回任何东西。谢谢!

Answer 1

return 语句用于停止函数。

您可以提供一个可选的返回值，但在这种情况下，我相信它会被忽略，因此您应该能够将 break; 替换为 return; .

---

旁注，但是您有很多重复代码，并且您在 if 条件中进行了分配。您通常可以排除重复。此外，如果您使用 if/else if/else 语句，则可以完全摆脱 return。

这是一个例子。

function isEmpty(val) {
    return val === "" || val == null;
}

function renderWithError(req, res, msg) {
    res.render('signup', { "title": "Ttitle", "menu": "signup", user: req.user, "error" : msg });
}

app.post('/signup', function(req, res) {
    if (isEmpty(req.body.first_name)) {
      renderWithError(req, res, "empty_first_name");
    }
    else if (isEmpty(req.body.last_name)) {
      renderWithError(req, res, "empty_last_name");
    }
    else if (isEmpty(req.body.email)) {
      renderWithError(req, res, "empty_email");
    }
    else if (req.body.password != req.body.repassword) {
      renderWithError(req, res, "pass_missmatch");
    }
    ...
    ...
    ...
    else {
        addUser(req.body.email, req.body.password, req.body.first_name, req.body.last_name, req.body.country, function(status) {
            res.render('signup', { "title": "Ttitle", "menu": "signup", user: req.user, "success" : 1 });
        });
    }
});

---