前后端分离，请求跨域问题。
1、已经在后端进行了跨域配置：
app.use('*', function (req, res, next) {
res.header('Access-Control-Allow-Origin', 'http://localhost:3001')
res.header('Access-Control-Allow-Headers', 'Content-Type, Content-Length, Authorization, Accept, X-Requested-With , yourHeaderFeild')
res.header('Access-Control-Allow-Methods', 'PUT, POST, GET, DELETE, OPTIONS')
res.header('Access-Control-Allow-Credentials', 'true')
res.header('X-Powered-By', ' 3.2.1')
res.header('Content-Type', 'application/json;charset=utf-8')
console.log(JSON.stringify(res.header))
if (req.method === 'OPTIONS') {
res.send(200)
} else {
var _send = res.send
var sent = false
res.send = function (data) {
if (sent) return
_send.bind(res)(data)
sent = true
}
next()
}
})
但是在前端请求时还是有问题：
解决（= =）：
这段代码需要写在api注册（app.use(api)）之前……
