CORS "It does not have HTTP ok status."

You may need to enable pre-flight requests for your route

app.use(cors())

app.options('/post/login', cors()) // enable pre-flight requests
app.post('/post/login', (req, res, next) => {
    // your code here
});

or for all routes

app.options('*', cors())

You can set the HTTP status of the pre-flight response.

app.options('*', function (req,res) { res.sendStatus(200); });