Postman "Sending request..." forever - node.js

Question

I am very new to node.js/express/postman so please excuse me if this question is pretty rookie. I have the following code produced from following an online tutorial. I used Postman to test it. The problem is, when I add the line app.use(express.json), Postman is unable to send the post request. It gets stuck at "Sending request...". If I exclude that one line then the "Get" requests will work. Anyone know why... based on this code. This is all of it:
Thanks!
const Joi = require('joi'); // Put required modules at the top
const express = require('express');
const app = express();
app.use(express.json);
const courses = [
{ id: 1, name: 'course1' },
{ id: 2, name: 'course2' },
{ id: 3, name: 'course3' },
];
app.get('/', (req, res) => {
res.send('Hello world!!!');
});
app.get('/api/courses', (req, res) => {
res.send(courses);
});
app.post('/api/courses', (req, res) => {
const { error } = validateCourse(req.body);
if (error) return res.status(400).send(results.error.details[0].message);
const course = {
id: courses.length + 1,
name: req.body.name
};
courses.push(course);
res.send(course); // assigning the id on the server. return course to client
});
app.get('/api/courses/:id', (req, res) => {
const course = courses.find(c => c.id === parseInt(req.params.id))
if (!course) return res.status(404).send('The course with the given ID was not found');
res.send(course);
});
app.put('/api/courses/:id', (req, res) => {
const course = courses.find(c => c.id === parseInt(req.params.id))
if (!course) return res.status(404).send('The course with the given ID was not found');
const { error } = validateCourse(req.body);
if (error) return res.status(400).send(results.error.details[0].message);
course.name = req.body.name;
res.send(course);
});
app.delete('/api/courses/:id', (req, res) => {
const course = courses.find(c => c.id === parseInt(req.params.id))
if (!course) return res.status(404).send('The course with the given ID was not found');
const index = courses.indexOf(course);
courses.splice(index, 1);
res.send(course);
})
function validateCourse(course) {
const schema = {
name: Joi.string().min(3).required()
};
return Joi.ValidationError(course, schema);
}
// PORT
const port = 3000;
app.listen(port, () => console.log(`listening on port ${port}...`));

Answer 1

You're issue is the json middleware (app.use(express.json);), which requires you to return valid JSON (Content-Type: application/json).
I got your sample running, by updating it to the following:
app.get('/', (req, res) => {
res.json({msg: 'Hello world!!!'});
});
Here's a working version: https://pastebin.com/06H6LCD2

Answer 2

Try:
app.use(express.json({ extended: false }));