NodeJS study notes (Url, QueryString, Path) module_node.js

1, opening analysis

This article discusses these three modules together because their respective lengths are not very long. Secondly, there are dependencies between them, so they are introduced in turn and analyzed with examples. Without further ado, please take a look at the following document:

(1), "Url module"

Here’s a little chestnut:

Copy code The code is as follows:

var url = require('url');
var queryUrl = "http://localhost:8888/bb?name=bigbear&memo=helloworld" ;
console.log(typeof url.parse(queryUrl)) ;
console.log(url.parse(queryUrl)) ;

Running results:

Copy code The code is as follows:

object // typeof

{
Protocol: 'http:',
​​slashes: true,
auth: null,
Host: 'localhost:8888',
Port: '8888',
Hostname: 'localhost',
hash: null,
Search: '?name=bigbear&memo=helloworld',
Query: 'name=bigbear&memo=helloworld',
Pathname: '/bb',
Path: '/bb?name=bigbear&memo=helloworld',
href: 'http://localhost:8888/bb?name=bigbear&memo=helloworld'
}

The explanation is as follows:

protocol: request protocol
Host: URL host name has been converted to lowercase, including port information
auth: The authentication information part in the URL
Hostname: The host name part of the host, has been converted to lowercase
Port: The port number part of the host
Pathname: The path part of the URL, located after the host name and before requesting the query
Search: The "query string" part of the URL, including the leading question mark.
Path: pathname and search are connected together.
Query: The parameter part in the query string (the part of the string after the question mark), or the object returned after parsing using querystring.parse().
​Hash: The part after the “#” in the URL (including the # symbol)

Supplementary API: "url.format(urlObj)"
​

Function: Input a URL object and return the formatted URL string.

(2), "QueryString module"

The "QueryString" module is used to convert URL parameter strings and parameter objects to and from each other. Here is an example, as shown below:

Copy code The code is as follows:

var url = require('url');
var qs = require('querystring');
var queryUrl = "http://localhost:8888/bb?name=bigbear&memo=helloworld" ;
queryUrl = url.parse(queryUrl).query ;
console.log(queryUrl) ;
console.log(qs.parse(queryUrl)) ;

The running results are as follows:

Copy code The code is as follows:

　　name=bigbear&memo=helloworld
　　{
name: 'bigbear',
　　memo: 'helloworld'
　　}

Supplementary API:

Querystring.stringify(obj, [sep], [eq])------Serialize an object into a query string.

You can choose whether to override the default separator ('&') and distribution character ('=').　　　　　

Querystring.stringify({foo: 'bar', baz: 'qux'}, ';', ':')// Returns the following string 'foo:bar;baz:qux'

　querystring.parse(str, [sep], [eq], [options])------Deserialize a query string into an object. You can choose whether to override the default delimiter ('&') and distribution character ('=').
​
The options object may contain the maxKeys attribute (default is 1000), which can be used to limit the number of keys processed. Setting it to 0 can remove the limit on the number of keys.
​
Example: querystring.parse('foo=bar&baz=qux&baz=quux&corge') // { foo: 'bar', baz: ['qux', 'quux'], corge: '' }

(3), "Path module"

This module contains a set of tools for processing and converting file paths. Almost all methods only convert strings, and the file system does not check whether the path is real and valid.

Let’s start with a simple chestnut: 　　

Copy code The code is as follows:

var url = require('url');
var qs = require('querystring');
var path = require("path") ;
var queryUrl = "http://localhost:8888/bb?name=bigbear&memo=helloworld" ;
var root = path.basename(queryUrl) ;
console.log(root); // bb?name=bigbear&memo=helloworld

Returns the last part of the path, separated by "/".

Copy code The code is as follows:

var url = require('url');
var qs = require('querystring');
var path = require("path") ;
var queryUrl = "http://localhost:8888/bb?name=bigbear&memo=helloworld" ;
var root = path.basename(queryUrl) ;
console.log(root); // bb?name=bigbear&memo=helloworld
var ext = path.extname(root) ;
console.log(ext || "Not Ext Name !") ; // Not Ext Name !

Since there are too many APIs, only a few commonly used ones are listed above. You need to read the documentation carefully.

Two, comprehensive chestnuts

Scenario description------The server receives requests under different circumstances and handles them differently through "Url". The code is as follows:

(1), create "index.html"

Copy code The code is as follows:

 
 
    
        
        
        
        
        
    
    
        

Hello,大熊！

    
 

　　（2），建立”index.js“

alert("Hello bb !") ; // 为了测试就这么一句代码
　　（3），建立”server.js“

复制代码 代码如下:

var http = require("http");
var fs = require('fs');
var url = require('url');
var path = require("path") ;
http.createServer(function(request,response) {
    var method = request.method ;
    method = method.toLowerCase() ;
    var fileName = path.basename(request.url) ;
    var extName = path.extname(fileName) ;
    var root = "./" ;
    if("get" == method){
        if(extName){
            fs.readFile("./" fileName,"utf-8",function (error,data){
                if(error)throw error ;
                response.writeHead(200,{
                    "Content-Type": {
                         ".css": "text/css" ,
                         ".js" : "application/javascript"
                  }[extName]
                }) ;
                response.write(data) ;
                response.end() ;
            });
        }
        else{
            fs.readFile(root "index.html","utf-8",function (error,data){
                if(error)throw error ;
                response.writeHead(200,{
                    "Content-Type" : "text/html"
                });
                response.write(data) ;
                response.end() ;
            });
        }
    }
    else if("post" == request.url){
        // handle post here
    }
}).listen(8888) ;
console.log("Web Server Running , Port On ---> 8888") ;

 
　　node server.js 运行一下。

三，总结一下

（1），理解上述三个模块之间的联系，灵活使用 。
（2），熟练使用 "Url，QueryString，Path" 三个模块相关的api。
（3），最后强调：理解上面例子中的代码意图，不断重构，不断总结。