Detailed explanation of URLs in nodeJS

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In the HTTP part, the relevant knowledge of URL is introduced in detail. The url module in nodejs provides some practical functions for URL processing and parsing. This article will introduce in detail the URL object in nodeJS

URL object

Parsing the URL object has the following contents, depending on whether they exist in the URL string. Any part that is not in the URL string will not appear in the parsed object

'http://user:pass@host.com:8080/p/a/t/h?query=string#hash'

┌─────────────────────────────────────────────────────────────────────────────┐
│                                    href                                     │
├──────────┬┬───────────┬─────────────────┬───────────────────────────┬───────┤
│ protocol ││   auth    │      host       │           path            │ hash  │
│          ││           ├──────────┬──────┼──────────┬────────────────┤       │
│          ││           │ hostname │ port │ pathname │     search     │       │
│          ││           │          │      │          ├─┬──────────────┤       │
│          ││           │          │      │          │ │    query     │       │"  http:   // user:pass @ host.com : 8080   /p/a/t/h  ?  query=string   #hash "│          ││           │          │      │          │ │              │       │
└──────────┴┴───────────┴──────────┴──────┴──────────┴─┴──────────────┴───────┘

[href]: The complete URL to be parsed, including the protocol and host (lowercase)

'http://user:pass@host.com:8080/p/a/t/h?query=string#hash'

[protocol]: request protocol, lowercase

'http:'

[slashes]: slash (colon) required by the protocol After)

true 或 false

[host]: The complete lowercase host part of the URL, including port information

'host.com:8080'

[auth]: Verification in the url Information

'user:pass'

[hostname]: The lowercase host name in the domain name

'host.com'

[port]: The port number of the host

'8080'

　[pathname]: The path part in the URL, after the host name and before the query character, contains the first slash

'/p/a/t/h'

　[search]: The query string in the URL contains the question mark at the beginning

'?query=string'

[path]: pathname and search are connected together

'/p/a/t/h?query=string'

[query] : The parameter part in the query string, or the object returned after parsing using querystring.parse()

'query=string' or {'query':'string'}

[hash]: The part after the "#" of the URL (including the # symbol)

'#hash'

URL method

The URL module contains tools for analyzing and parsing URLs. Call require('url') to access the module

var url = require('url');/*{ parse: [Function: urlParse],
  resolve: [Function: urlResolve],
  resolveObject: [Function: urlResolveObject],
  format: [Function: urlFormat],
  Url: [Function: Url] } */console.log(url);

[url.parse(urlStr[, parseQueryString][, slashesDenoteHost])】

Enter the URL string, Return an object

The second parameter parseQueryString (default is false), if it is false, urlObject.query is an unparsed string, such as author=%E5%B0%8F%E7%81%AB %E6%9F%B4, and the corresponding value will not be decoded; if parseQueryString is true, then urlObject.query is object, such as { author: 'Little Match' }, and the value will be decoded

Third parameter slashesDenoteHos (default is false), if it is true, URLs without protocol headers can be correctly parsed, similar to foo in //foo/bar, which will be considered hostname; if it is false, foo will be considered pathname. Part of

var url = require('url');var str = 'http://user:pass@host.com:8080/p/a/t/h?author=%E5%B0%8F%E7%81%AB%E6%9F%B4#hash';/*Url {
  protocol: 'http:',
  slashes: true,
  auth: 'user:pass',
  host: 'host.com:8080',
  port: '8080',
  hostname: 'host.com',
  hash: '#hash',
  search: '?author=%E5%B0%8F%E7%81%AB%E6%9F%B4',
  query: 'author=%E5%B0%8F%E7%81%AB%E6%9F%B4',
  pathname: '/p/a/t/h',
  path: '/p/a/t/h?author=%E5%B0%8F%E7%81%AB%E6%9F%B4',
  href: 'http://user:pass@host.com:8080/p/a/t/h?author=%E5%B0%8F%E7%81%AB%E6%9F%B4#hash' } */console.log(url.parse(str));

var url = require('url');var str = 'http://user:pass@host.com:8080/p/a/t/h?author=%E5%B0%8F%E7%81%AB%E6%9F%B4#hash';/*Url {
  protocol: 'http:',
  slashes: true,
  auth: 'user:pass',
  host: 'host.com:8080',
  port: '8080',
  hostname: 'host.com',
  hash: '#hash',
  search: '?author=%E5%B0%8F%E7%81%AB%E6%9F%B4',
  query: { author: '小火柴' },
  pathname: '/p/a/t/h',
  path: '/p/a/t/h?author=%E5%B0%8F%E7%81%AB%E6%9F%B4',
  href: 'http://user:pass@host.com:8080/p/a/t/h?author=%E5%B0%8F%E7%81%AB%E6%9F%B4#hash' }  */console.log(url.parse(str,true));

var url = require('url');var str = '//foo/bar';var result1 = url.parse(str,true);var result2 = url.parse(str,true,true);
console.log(result1.path);//'//foo/bar'console.log(result1.pathname);//'//foo/bar'console.log(result1.hostname);//nullconsole.log(result2.path);//'/bar'console.log(result2.pathname);//'/bar'console.log(result2.hostname);//'foo'

【url.format(urlObject)】

　The reverse of url.parse(str) To operate, enter a parsed URL object and return a formatted string

The urlObject contains many fields, such as protocol, slashes, protocol, etc., and it is not necessarily necessary to pass them all, so there is a set of parsing logic

The formatting workflow is as follows

href 会被忽略
protocol 无论是否有末尾的 : (冒号)，会同样的处理
http, https, ftp, gopher, file 协议会被添加后缀://mailto, xmpp, aim, sftp, foo, 等协议添加后缀:
slashes 如果协议需要 ://，设置为 true仅需对之前列出的没有斜杠的协议，比如议 mongodb://localhost:8000/auth 如果出现将会使用.
hostname 仅在缺少 host 时使用
port 仅在缺少 host 时使用
host 用来替换 hostname 和 port
pathname 无论结尾是否有 / 将会同样处理
search 将会替代 query属性
无论前面是否有 / 将会同样处理
query (对象; 参见 querystring) 如果没有 search,将会使用
hash 无论前面是否有#，都会同样处理

var url = require('url');var obj = {
  protocol: 'http:',
  auth: 'user:pass',
  host: 'host.com:8080',
  hash: '#hash',
  query: { author: '小火柴' }
}//http://user:pass@host.com:8080?author=%E5%B0%8F%E7%81%AB%E6%9F%B4#hashconsole.log(url.format(obj));

【url.resolve(from, to)】

url. The resolve() method resolves a target URL relative to a base URL in a way that a browser parses hyperlinks. The parameters are as follows

from <String> 解析时相对的基本 URL。
to <String> 要解析的超链接 URL。

var url = require('url');
console.log(url.resolve('/one/two/three', 'four'));         // '/one/two/four'console.log(url.resolve('http://example.com/', '/one'));    // 'http://example.com/one'console.log(url.resolve('http://example.com/one', '/two')); // 'http://example.com/two'

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