Normally, a function is passed as callback in app.use(), like so:
const express = require('express');
const app = express();
app.use(function (req, res, next) {
console.log('Time:', Date.now());
next();
});
In the case of node-expose-sspi however a method is passed:
const express = require('express');
const { sso } = require('node-expose-sspi');
const app = express();
app.use(sso.auth()); //stores something in req.sso
app.use((req, res, next) => {
res.json({
sso: req.sso,
});
});
Why is the method passed with ()? If it uses () why is it no called immediately (without arguments)?
Also, how can I wrap a method in a callback function, e.g.
app.use(myCallback);
function myCallback(req, res, next) {
sso.auth(); //req.sso is undefined
}
app.use(sso.auth());
calls sso.auth() and app.use()s its return value.
You can find over here in the node-expose-sspi source that .auth() indeed returns a new middleware function.
As for the second question
Also, how can I wrap a method in a callback function
you shouldn't do that – Express will call your used middlewares in order; a subsequent callback will have access to whatever a previous middleware has injected into the request.
If you for some reason really need to do that,
const ssoAuth = sso.auth();
function myCallback(req, res, next) {
ssoAuth(req, res, () => {
// whatever would regularly be in `myCallback`
next();
});
}
``