index.js

const Joi = require('joi');
const express = require('express');
const app=express();

app.use(express.json());//middleware 

const courses = [
    {id:1, name:'math'},
    {id:2, name:'science'},
    {id:3, name:'history'}];

app.get('/', (req, res) => {
    res.send('Wasssssa');
});

app.get('/api/courses', (req, res) => {
    res.send(courses);
});

//route params
app.get('/api/doj/:dd/:mm/:yyyy', (req, res) => {
    res.send(req.params);
});

//GET requests
app.get('/api/courses/:id', (req, res) => {
    let course = courses.find(c => c.id === parseInt(req.params.id));
    if(!course) res.status(404);
    res.send(course);
});

//POST requests
app.post('/api/courses', (req, res) => {
    const schema = { name: Joi.string().min(3).required()};
    let result = Joi.valid(req.body, schema);
    
    if(result.error){
        res.status(400).send('name is required');
        return;
    }
    let course = {
        id: courses.length + 1, 
        name: req.body.name
    };
    courses.push(course);
    res.send(course);
});


//Update requests
app.put('/api/courses/:id', (req, res) => {
    let course = courses.find(c => c.id === parseInt(req.params.id));
    if (!course) res.status(404);

    const schema = { name: Joi.string().min(3).required() };
    let result = Joi.valid(req.body, schema);
    if (result.error) {
        res.status(400).send('name is required');
        return;
    }

    course.name = req.body.name;
    res.send(course);
});


//delete requests
app.delete('/api/courses/:id', (req, res) =>{
    let course = courses.find(c => c.id === parseInt(req.params.id));
    if (!course) res.status(404);

    const ind = courses.indexOf(course);
    courses.splice(ind, 1);

    res.send(course);
});

//env var
const port=3000;
app.listen(port, () => console.log(`Listening on port ${port}...`));