我已经构建了一个带有node.js的webapp，通过POST请求从SNS主题接收消息，并将它们记录到控制台，然后在网页上显示它们，如果我向主题发布消息，我会在控制台中打印消息，但没有在我的网页上更新？
这是我的app.js代码
const express = require("express");
const request = require('request')
const bodyParser = require('body-parser')
const app = express();
app.use(express.static('public'));
app.set("view engine", "ejs")
app.get('/', function (req, res) {
let subject = "Your Subject Will Appear Here";
let message = "Your Message Will Appear Here";
res.render("index", {subject:subject, message:message});
})
app.use(bodyParser.urlencoded({ extended: false }))
app.use(bodyParser.json())
app.post('/', (req, res) => {
let body = ''
req.on('data', (chunk) => {
body += chunk.toString()
})
req.on('end', () => {
let payload = JSON.parse(body)
if (payload.Type === 'Notification') {
console.log(payload.Message);
let subject = payload.Subject;
let message = payload.Message;
res.render("index", {subject:subject, message:message});
}
});
});
app.listen(80, process.env.IP, function(request, response){
console.log("## SERVER STARTED ##");
});
这是我的index.js代码
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>title</title>
<link rel="stylesheet" type="text/css" href="/css/style.css">
<link href='https://fonts.googleapis.com/css?family=Open+Sans:300' rel='stylesheet' type='text/css'>
</head>
<body>
<div class="container">
<fieldset>
<% if(subject !== null){ %>
<p>SNS Subject: <%= subject %></p>
<% } %>
<% if(message !== null){ %>
<p>SNS Message: <%= message %></p>
<% } %>
</fieldset>
</div>
</body>
</html>
因为你的变量是get和post回调函数中的局部变量。如果您希望它们超出这些回调的范围，则需要将它们移动到回调返回时不会消失的范围。
例如，这使得它们成为模块全局变量但是对于每个POST而言，无论它来自哪个，它都会变得奇怪，以改变无关GET的内容（请参阅***注释）：
// *** Declared at module scope
let subject = "Your Subject Will Appear Here";
let message = "Your Message Will Appear Here";
app.get('/', function (req, res) {
// *** Not declared here
res.render("index", {subject:subject, message:message});
})
// ...
app.post('/', (req, res) => {
let body = ''
req.on('data', (chunk) => {
body += chunk.toString()
})
req.on('end', () => {
let payload = JSON.parse(body)
if (payload.Type === 'Notification') {
console.log(payload.Message);
subject = payload.Subject; // <======= *** no `let`, we're not declaring here
message = payload.Message; // <======= *** same
res.render("index", {subject:subject, message:message});
}
});
});
但同样，这可能没有意义。您可能需要某种每用户或每会话存储机制（例如数据库，或内存缓存过期等）。