app.post('/users', (req, res) => {
const user = req.body;
user.id = users.length + 1;
users.push(user);
res.send(user)
});
const { id } = req.body;
index.html
<form action="/test" method="POST">
<input name="abc" />
<input type="submit value="submit"/>
</form>
routers/index.js
router.post("/test", function(req, res, next){
res.send(req.body.abc);
}