10 . 跨域之CORS

本节内容已在网络篇详解跨域之CORS

设置跨域的中间件

const allowOrigins = ['http://localhost:3333', null]
module.exports = function (req, res, next) {
    // 处理预检请求
    if (req.method === 'OPTIONS') {
        res.header('Access-Control-Allow-Methods', req.headers['access-control-request-method']);
        res.header("Access-Control-Allow-Headers", req.headers['access-control-request-headers']);//允许的header类型
    }
    // 处理附带身份凭证的请求(cookie)
    res.header("Access-Control-Allow-Credentials", true)
    // 处理简单请求
    if ('origin' in req.headers && allowOrigins.includes(req.headers.origin)) {
        res.header("Access-Control-Allow-Origin", req.headers.origin);
    }
    next();
}