如何将get函数中的数据从node.js中的同一个js文件中的另一个函数中获取？

Question

I want to get data out of a router.get() function to another function located in the same JS file.

I have a data sent to a get method:

router.get('/', function(req, res, next) {
  res.render('index', { title: 'Express' });
});

Now I want to use title variable in another method:

router.post('/', function(req, res) {
 // I want to use the title variable in here
});

Any help would be appreciated.

Answer 1

You just need to change the scope of the variable. Be careful though when expanding the scope of variables. Ie, you would set the title outside of your router callbacks, and then reference it inside. Also, as your web app grows, it's possible you'll have many different pages, each with their own page titles.

The easy way to make this work is to initialize the title outside the route handler:

// Here, I'm using Object.freeze, assuming you want the map to be 
// immutable (i.e., not accidentally changed by other parts of the code)
// (const titles = { ... } won't achieve it)
let titles = Object.freeze({ /* Formatted as a "route" --> "title" map */
  index: 'Express'    
});

router.get('/', function(req, res, next) {
  const routeName = 'index'
  res.render(routeName, { title: titles[routeName] });
});

router.post('/', function(req, res) {
  const routeName = 'index'
  // Access your title here:
  console.log(titles[routeName]);
});

As an alternative, expressJS allows us to use app.get() and app.set() methods. Usually most expressJS apps start out like this:

let app = express();

You can stash variables associated with the app like this:

app.set('indexTitle', 'Express');

So that way in your route handler, you can access like this:

router.get('/', function(req, res, next) {
  res.render(routeName, { title: app.get('indexTitle') });
});

router.post('/', function(req, res) {
  // Access your title here:
  console.log(app.get('indexTitle'));
});

Yet, an even easier approach may be to let the front-end keep track of all the page titles, and, if the title is absolutely something the back-end needs, the front-end can simply post that in the req.body . Yes, might be overkill, but it would eliminate the need for the server to keep track of it:

router.post('/', function(req, res) {
  // Access your title here:
  console.log(req.body.pageTitle);
});