How does the front end interact with node.js via ajax?

Question

First of all, my file structure:
web
-public
--login.html (the login page is a static page)
-veiws
--index.jade
- routes
--index.js
-app.js
Front-end code

$("#login").click(function(){
        var username=$('#un').val();
        var pw=$("#pw").val();
        var data = {"un":username,"pw":pw};
        $.ajax({
            type:"post",
            url:"/login",
            async:true,
               success: function(data,status){ 
                    if(status == 'success'){ 
                        location.href = '../views/index.jade';
                    }
                },
                error: function(data,status){ 
                    if(status == 'error'){ 
                        alert("密码或者用户名错误");
                    }
        });
    })

What should I write in the url in $.ajax?
In addition, should my server code be written in app.js or index.js in the router folder? Or create a new js file and write the server code into it, and then write the relative directory of the js file in the URL (this seems to be the case with PHP).
There is also router.get('/', function(req, res, next){}) in index.js and var router = require('./routes/index) in
app.js ');app.use('/',router) What is the difference? Which one is the binding domain name? My understanding is that after the server is started, app.js is automatically run and then app.use is equivalent to pushing the functions into a stack and executing them sequentially. Then when index.js is executed, index.js renders the jade template in views according to the URL address, and every Refresh and re-render (it’s not clear whether app.js is re-executed without refreshing or index.js is re-executed).

Answer 1

You can try entering the following code in segmentFault’s console

$.ajax({
    url: '/',
    success: res => console.log(res), 
    error: err => console.log(err)
}); 

---

Then you will get / the content of this html file.

---

Your question

Suppose you are listening on port 3000 and you have defined the /login route

Then the URL should be /login

---

The content behind app.use is called middleware

For example, I visit http://localhost:3000/api/login

It just so happens that I have a middleware that can match /api/login. Then express will hand over req res to this middleware for processing

Answer 2

URL can be relative or absolute. Starting from http(s)://, you can specify the URL on any domain name, but please pay attention to the issue of cross-domain access. Relative is the URL relative to the current page,

url	Explanation
/<path>	The relative path starting with /, relative to the root, which is the Domain (host domain name) where the current page is located
../<path>	Start from the upper path where the current page is located. Multiple ../ can be used together to represent the upper layers
./	Start from the same path of the current page, and don’t ./ have the same effect

What needs to be noted here is the identification of the current page path, because folder/ in the URL can be abbreviated to folder, and whether or not folder/ 有可简写成 folder，而有没有 / represents a completely different location (in today’s world When routing is widely used, directories or pages are no longer distinguished by extensions), so it is generally recommended that the front end at least write a path relative to the root.

Answer 3

You write '/' to represent the current port, and url is your path in nodejs