express 配置前端跨域访问

app.use(function(req,res,next){

res.header('Access-Control-Allow-Origin', '*');

res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');

res.header('Access-Control-Allow-Headers', 'Content-Type');

res.header("Content-Type", "application/json;charset=utf-8");

res.header('Access-Control-Allow-Credentials','true');

next();

})