无法在我的快递应用中解决 CORS 政策

Posted 2023-02-27

【中文标题】无法在我的快递应用中解决 CORS 政策

【英文标题】：Can't solve CORS policy in my express app

【发布时间】：2020-05-09 13:36:31

【问题描述】：

我一直收到这个错误

被 CORS 策略阻止：请求的资源上不存在“Access-Control-Allow-Origin”标头。如果不透明的响应满足您的需求，请将请求的模式设置为“no-cors”以获取禁用 CORS 的资源。

这是我的 Express 代码

const express = require('express')
const app = express()
const port = 3001

var redis = require("redis"),
    client = redis.createClient();

const promisify = require('util')
const getAsync = promisify(client.get).bind(client);

app.get('/jobs', async (req, res) => 
    const jobs = await getAsync('github');
    res.header("Access-Control-Allow-Origin", "http://localhost:3000");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
    return res.send(jobs);
)

app.listen(port, () => console.log(`Example app listening on port $port!`))

【问题讨论】：

你试试这个？ expressjs.com/en/resources/middleware/cors.html

能否也添加客户端请求

我遇到了一些不久前解决的 cors 问题。这是我对 SO 提出的问题：***.com/questions/50860526/…

【参考方案1】：

尝试cors 中间件包以在 express 应用中启用内核。

安装为生产依赖项。

npm install --save cors

例子：

const express = require('express');
const cors = require('cors');
const app = express();
const port = 3001
var redis = require("redis"),
    client = redis.createClient();
const  promisify  = require('util')
const getAsync = promisify(client.get).bind(client);
const allowedOrigins = ["http://localhost:3000"];

app.use(cors(
    origin: function (origin, callback) 
        if (!origin) return callback(null, true);
        if (allowedOrigins.indexOf(origin) === -1) 
            var msg = 'The CORS policy for this site does not ' +
                'allow access from the specified Origin.';
            return callback(new Error(msg), false);
        
        return callback(null, true);
    
));

app.get('/jobs', async (req, res) => 
    const jobs = await getAsync('github');
    res.header("Access-Control-Allow-Origin", "http://localhost:3000");
    res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
    return res.send(jobs);
)
app.listen(port, () => console.log(`Example app listening on port $port!`))