在 Express.js 中发送错误消息并重定向

Question

Learning Express.js.学习 Express.js。 I have the following simple HTML form:我有以下简单的 HTML 表格：

<!DOCTYPE html>
<html lang="en" dir="ltr">
  <head>
    <meta charset="utf-8">
    <title>Calculator</title>
  </head>
  <body>
    <h1>Calculator</h1>
    <form action="/" method="post">
      <input type="text" name="num1" placeholder = "First Number" value=""> <br>
      <input type="text" name="num2" placeholder = "Second Number" value=""> <br>
      <button type="submit" name="submit">Calculate</button>
    </form>
  </body>
</html>

The user is supposed to input two numbers, and their sum is returned to them.用户应该输入两个数字，然后将它们的总和返回给它们。 The simple Express server is here.简单的 Express 服务器在这里。 body-parser is included in node_modules and use d by the Express app in order to manipulate the req object and extract the form data. body-parser包含在node_modules中，Express app use d 来操作req object 并提取表单数据。

const express = require("express");
const bodyParser = require("body-parser");
const app = express();

app.use(bodyParser.urlencoded({extended:true}));

app.listen(3000, () => {
  console.log("Server spun on port 3000.")
});

app.get("/", (req, res) => {
  console.log("Serving a GET request at root route.");
  res.sendFile(absoluteDirPath() + "index.html");
});

app.post("/", (req, res) => {
  console.log("Serving a POST request at root route.");
  let num1 = Number(req.body.num1);
  let num2 = Number(req.body.num2);
  if(isNaN(num1) || isNaN(num2)) {
     res.send("<p>Need numerical values.</p>"); 
   } else {
    res.send("<h3>Result: " + (num1 + num2) + "</h3>");
  }
  // How can I re-direct the user here? 
});

function absoluteDirPath() {
  const path = require('path');
  return __dirname + path.sep;
}

I am interested in redirecting the user to index.html in the POST middleware so that they can use the calculator again without refreshing the URL, whether they used it successfully or not.我有兴趣将用户重定向到POST中间件中的index.html以便他们可以再次使用计算器而无需刷新 URL，无论他们是否成功使用它。 Since this is in the backend, I don't have access to the window object and I can't play around with it directly.由于这是在后端，我无法访问window object 并且我无法直接使用它。 Not sure how this could be done.不确定如何做到这一点。 Any ideas?有任何想法吗？

Answer 1

To redirect in express:快速重定向：

res.redirect('/');

This doesn't exactly similate window.location , but it does redirect.这并不完全类似于window.location ，但它确实重定向。

However, I don't see why you should redirect, because you are sending the client a message, and before they get to see it you already redirected them.但是，我不明白您为什么应该重定向，因为您正在向客户端发送消息，并且在他们看到它之前您已经重定向了他们。

A better way to approach your problem would be to use AJAX (submitting a form without reloading the page);解决问题的更好方法是使用 AJAX （提交表单而不重新加载页面）； check out this jQuery example (client-side obviously):查看此 jQuery 示例（显然是客户端）：

function submitFormWithoutReloading() {
   $.ajax({
      type: "POST",
      url: "/",
      data: {
         num1: $('#idOfYourFirstInput').val(),
         num2: $('#idOfYourSecondInput').val()
      },
      success: function(res) {
         alert(res); // This is what the server returns
      }
   });
}

Also, you can just use the provided variable __dirname for the absolute path.此外，您可以只使用提供的变量__dirname作为绝对路径。

在 Express.js 中发送错误消息并重定向

问题描述

1 个解决方案

解决方案1
0 已采纳 2021-05-08 02:59:27

在 Express.js 中发送错误消息并重定向

问题描述

1 个解决方案

解决方案1 0 已采纳 2021-05-08 02:59:27

解决方案1
0 已采纳 2021-05-08 02:59:27