javascript - 无法解决我的 Express 应用中的 CORS 政策

Question

我不断收到此错误

blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

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}!`))

Answer 1

尝试使用 cors 中间件包在 Express 应用中启用内核。

作为生产依赖项安装。

npm install --save cors

示例:

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}!`))