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JS all network request modes

2022-06-27 10:16:00 【Xiaaoke】

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HTTP

HTTP（hypertext transport protocol） agreement 『 Hypertext transfer protocol 』, The protocol specifies the rules of communication between browser and World Wide Web server .

Request message

The focus is on format and parameters 

 That's ok       POST  /s?ie=utf-8  HTTP/1.1 
 head       Host: atguigu.com
        Cookie: name=guigu
        Content-type: application/x-www-form-urlencoded
        User-Agent: chrome 83
 Blank line 
 body       username=admin&password=admin

response message 

 That's ok       HTTP/1.1  200  OK
 head       Content-Type: text/html;charset=utf-8
        Content-length: 2048
        Content-encoding: gzip
 Blank line     
 body       <html>
            <head>
            </head>
            <body>
                <h1> Silicon Valley </h1>
            </body>
        </html>

Common status codes

  • 1XX： Specify some actions corresponding to the client
  • 2XX： success
  • 3XX： A file that has been moved and is contained in the location header information （ Redirect , In order to complete the request , Required actions ）
  • 4XX： Client error
  • 5XX： Server error
  • 404： No files found
  • 403： The server has been requested , But refuse to execute
  • 401： Current request requires user authentication
  • 400： Invalid request
  • 500： Server internal problems
  • 200： The request is successful
  • 304： not changed , The requested resource has not been modified

readyState attribute

  • 0： uninitialized （Uninitialized）. Not yet invoked open() Method .
  • 1： Already opened （Open）. Already called open() Method , Not yet invoked send() Method .
  • 2： Has been sent （Sent）. Already called send() Method , No response has been received .
  • 3： Receiving （Receiving）. Partial response has been received .
  • 4： complete （Complete）. All responses have been received , It's ready to use

Native AJAX

AJAX brief introduction

  • AJAX Its full name is Asynchronous JavaScript And XML, It's asynchronous JS and XML.
    • asynchronous ： Will not occupy js The main thread , Instead, call the child threads of the thread pool （ Network request thread ）
    • The implementation syntax is mainly JavaScript
    • xml： Belong to html Brother . Because it is too troublesome to parse , All are now gradually being json Instead of
  • adopt AJAX You can send asynchronous requests to the server in the browser , The biggest advantage ： No refresh to get data .
  • AJAX It's not a new programming language , It is a new way to combine existing standards .

XML brief introduction

  • XML Extensible markup language .
  • XML Designed to transmit and store data .
  • XML and HTML similar , The difference is HTML Are predefined labels in , and XML There are no predefined labels in ,
  • It's all custom labels , Used to represent some data .

For example, I have a student data ：name = " The Monkey King " ; age = 18 ; gender = " male " ;

//  use  XML  Express ：
<student>
  <name> The Monkey King </name>
  <age>18</age>
  <gender> male </gender>
</student>

//  use  JSON  Express ：
{
    "name":" The Monkey King ","age":18,"gender":" male "}

Now it's basically JSON To replace the .

AJAX Characteristics

AJAX The advantages of

  • You can communicate with the server without refreshing the page .
  • Allows you to update some page content according to user events .

AJAX The shortcomings of

  • No browsing history , Can't back
  • There are cross-domain problems ( Homology )
  • SEO unfriendly

AJAX Use

The core object ：XMLHttpRequest,AJAX All operations of are performed through this object 

// 1)  establish  XMLHttpRequest  object 
let xhr = null;
if (window.XMLHttpRequest) {
    
  xhr = new XMLHttpRequest();
  } else {
    
  // code for IE6, IE5
  xhr = new ActiveXObject("Microsoft.XMLHTTP");
}

// Set the type of response body data 
xhr.responseType = 'json';

// timeout  2s  Set up 
xhr.timeout = 2000;
// Timeout callback 
xhr.ontimeout = function(){
    
    alert(" Network anomalies ,  Please try again later !!");
}
// Network exception callback 
xhr.onerror = function(){
    
    alert(" There seems to be something wrong with your network !");
}

// 2)  Set request information 
xhr.open(method, url); 
// You can set the request header , Generally not set 
xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');

// 3)  Send a request 
xhr.send(body) //get  Request not to transmit  body  Parameters , Only  post  Request to use 

// 4)  Receiving response 
//xhr.responseXML  receive  xml  Response data in format 
//xhr.responseText  The format of the response data 
//JSON.parse(xhr.response)  take json The file is converted to js data 
xhr.onreadystatechange = function() {
     
  if (xhr.readyState == 4) {
     
    if ((xhr.status >= 200 && xhr.status < 300) || xhr.status == 304) {
     
      console.log(xhr.responseText); //  The text returned as a response body 
    } else {
     
      console.log("Request was unsuccessful: " + xhr.status); //  request was aborted , return   Responsive  HTTP  state  
    } 
  } 
};

//  Cancel the request ：xhr.abort();

// get Request parameter splicing method 
const addURLParam = (url, name, value) => {
     
  url += (url.indexOf("?") == -1 ? "?" : "&"); 
  url += encodeURIComponent(name) + "=" + encodeURIComponent(value); 
  return url; 
}
// post Form transfer parameters 
let form = document.getElementById("user-info"); 
xhr.send(new FormData(form));

Usually write 1~4 Step by step

solve IE The cache problem

problem ： In some browsers (IE), Because of the cache mechanism ,ajax Only the first request will be sent , Remnant
The remaining requests are not sent to the browser, but directly load the data in the cache .

Solution ： The browser cache is based on url Address to record , So we just need to modify url Address
To avoid cache problems

xhr.open("get","/testAJAX?t="+Date.now());

ajax The state of return

  • 0：（ uninitialized ） Not called yet send() Method
  • 1：（ load ） Already called send() Method , Sending request
  • 2：（ Loading completed ）send() Method execution complete , All response contents have been accepted
  • 3：（ Interaction ） Parsing response content
  • 4：（ complete ） Response content parsing completed , Can be called on the client

jQuery-AJAX

get request

$.get(url, [data], [callback], [type])

  • url: Requested URL Address .
  • data: The parameter that the request carries .
  • callback: Callback function on load success .
  • type: Format the returned content ,xml, html, script, json, text, _default

post request

$.post(url, [data], [callback], [type])

  • url: Requested URL Address .
  • data: The parameter that the request carries .
  • callback: Callback function on load success .
  • type: Format the returned content ,xml, html, script, json, text, _default

ajax request 

$.ajax({
    
  //url
  url: 'http://127.0.0.1:8000/jquery-server',
  // Parameters 
  data: {
    a:100, b:200},
  // Request type 
  type: 'GET',
  // Response body results 
  dataType: 'json',
  // Successful callback 
  success: function(data){
    
      console.log(data);
  },
  // Timeout time 
  timeout: 2000,
  // Failed callback 
  error: function(){
    
      console.log(' Error !!');
  },
  // Header information 
  headers: {
    
      c:300,
      d:400
  }
});

Axios-AJAX

More detailed reference React Use in axios

get request 

// The default configuration 
axios.defaults.method = 'GET';// Set the default request type to  GET
axios.defaults.baseURL = 'http://localhost:3000';// Set the foundation  URL
axios.defaults.params = {
    id:100};
axios.defaults.timeout = 3000;//

// To configure  baseURL
axios.defaults.baseURL = 'http://127.0.0.1:8000';

axios.get('/axios-server', {
    
    //url  Parameters 
    params: {
    
        id: 100,
        vip: 7
    },
    // Request header information 
    headers: {
    
        name: 'atguigu',
        age: 20
    }
}).then(value => {
    
    console.log(value);
});

//  Cancel the request ：cancel();

post request 

// To configure  baseURL
axios.defaults.baseURL = 'http://127.0.0.1:8000';

axios.post('/axios-server', {
    
    username: 'admin',
    password: 'admin'
}, {
    
    //url 
    params: {
    
        id: 200,
        vip: 9
    },
    // Request header parameters 
    headers: {
    
        height: 180,
        weight: 180,
    }
});

ajax request 

//  The traditional way 
axios({
    
  methods: ' Request mode ', 
  url: ' Request address ',
  params: {
     // get
     Parameter name :  Parameter values 
  },
  data: {
     // post put patch
         Parameter name :  Parameter values 
  }
})
.then(res => {
     //  Processing after successful request 
  // res Is the response data returned by the server 
})
.catch(err => {
     //  Processing after a request fails 
  // err Is the information after the request fails 
})

// get request 
axios.get("url", {
    params: {
     Parameter name :  Parameter values }})
    .then(res => {
    
    })
    .catch(err => {
    
})

// post request ： Send form data and file upload 
axios.post("url", {
     Parameter name :  Parameter values })
    .then(res => {
    
    }).catch(err => {
    
})

// put request ： Update all data 
axios.put("url", {
     Parameter name :  Parameter values })
    .then(res => {
    
    }).catch(err => {
    
})

// patch request ： Update only changed data 
axios.patch("url", {
     Parameter name :  Parameter values })
    .then(res => {
    
    }).catch(err => {
    
})

// delete request ： Delete request （ Parameters can be placed in url On , Can also be combined with post Put it in the request body ）
axios.delete('url', {
    
    params: {
    
         Parameter name :  Parameter values 
    }
}).then(res => {
    
}).catch(err => {
    
})

axios.delete('url', {
    data: {
     Parameter name :  Parameter values }})
    .then(res => {
    
    })
    .catch(err => {
    
})

Fetch-AJAX

fetch('http://127.0.0.1:8000/fetch-server?vip=10', {
    
    // Request method 
    method: 'POST',
    // Request header 
    headers: {
    
        name:'atguigu'
    },
    // Request body 
    body: 'username=admin&password=admin'
}).then(response => {
    
    // return response.text();
    return response.json();
}).then(response=>{
    
    console.log(response);
});

Cross domain

The same-origin policy

The same-origin policy (Same-Origin Policy) The earliest by Netscape The company proposed , Is a security policy for browsers .

Homology ： agreement 、 domain name 、 Port number It must be exactly the same .

Violating the homology strategy is cross domain .

How to solve cross domain

JSONP

JSONP What is it?

JSONP(JSON with Padding), Is an unofficial cross domain solution , Rely solely on the ingenuity of programmers
Intelligence developed , Only support get request

JSONP How does it work ？

Some tags on Web pages are inherently cross domain , such as ：img link iframe script. JSONP Is the use script Tag's cross domain capability to send requests

JSONP Use 

// 1. Create a dynamic  script  label 
var script = document.createElement("script");
// 2. Set up  script  Of  src, Set the callback function 
script.src = "http://localhost:3000/testAJAX?callback=abc";
function abc(data) {
    
  alert(data.name);
};
// 3. take  script  Add to  body  in 
document.body.appendChild(script);

// 4. Processing of routing in the server 
router.get("/testAJAX" , function (req , res) {
    
  console.log(" Receive a request ");
  var callback = req.query.callback;
  var obj = {
    
    name:" The Monkey King ", 
    age:18
  }
  res.send(callback+"("+JSON.stringify(obj)+")");
});

jQuery-jsonp

$.getJSON('http://127.0.0.1:8000/jquery-jsonp-server?callback=?', function(data){
    
    $('#result').html(`  name : ${
      data.name}<br>  Campus : ${
      data.city} `)
});

CORS

CORS

CORS What is it? ？

CORS（Cross-Origin Resource Sharing）, Cross-domain resource sharing .CORS Is the official cross domain solution , Its characteristic is that it does not need to do any special operation on the client , Completely processed in the server , Support get and post request . A new set of standards for cross domain resource sharing has been added HTTP Header field , Allow the server to declare which origin has access to which resources through the browser

CORS How does it work ？

CORS It tells the browser by setting a response header , The request allows cross domain , The browser received the response
The response will be released later .

CORS Use 

//  Mainly server-side settings ：
router.get("/testAJAX" , function (req , res) {
    
  // adopt  res  To set the response header , To allow cross domain requests 
  //res.set("Access-Control-Allow-Origin","http://127.0.0.1:3000");
  res.set("Access-Control-Allow-Origin","*");
  res.send("testAJAX  Response returned ");
});

What is used node Service code 

//1.  introduce express
const express = require('express');

//2.  Create application objects 
const app = express();

//3.  Create routing rules 
// request  It is the encapsulation of request message 
// response  It is the encapsulation of response message 
app.get('/server', (request, response) => {
    
    // Set the response header   Set allow cross domain 
    response.setHeader('Access-Control-Allow-Origin', '*');
    // Set the response body 
    response.send('HELLO AJAX - 2');
});

// Can receive any type of request  
app.all('/server', (request, response) => {
    
    // Set the response header   Set allow cross domain 
    response.setHeader('Access-Control-Allow-Origin', '*');
    // Response head 
    response.setHeader('Access-Control-Allow-Headers', '*');
    // Set the response body 
    response.send('HELLO AJAX POST');
});

//JSON  Respond to 
app.all('/json-server', (request, response) => {
    
    // Set the response header   Set allow cross domain 
    response.setHeader('Access-Control-Allow-Origin', '*');
    // Response head 
    response.setHeader('Access-Control-Allow-Headers', '*');
    // Respond to a data 
    const data = {
    
        name: 'atguigu'
    };
    // String conversion of objects 
    let str = JSON.stringify(data);
    // Set the response body 
    response.send(str);
});

// in the light of  IE  cache 
app.get('/ie', (request, response) => {
    
    // Set the response header   Set allow cross domain 
    response.setHeader('Access-Control-Allow-Origin', '*');
    // Set the response body 
    response.send('HELLO IE - 5');
});

// Delayed response 
app.all('/delay', (request, response) => {
    
    // Set the response header   Set allow cross domain 
    response.setHeader('Access-Control-Allow-Origin', '*');
    response.setHeader('Access-Control-Allow-Headers', '*');
    setTimeout(() => {
    
        // Set the response body 
        response.send(' Delayed response ');
    }, 1000)
});

//jQuery  service 
app.all('/jquery-server', (request, response) => {
    
    // Set the response header   Set allow cross domain 
    response.setHeader('Access-Control-Allow-Origin', '*');
    response.setHeader('Access-Control-Allow-Headers', '*');
    // response.send('Hello jQuery AJAX');
    const data = {
    name:' Silicon Valley '};
    response.send(JSON.stringify(data));
});

//axios  service 
app.all('/axios-server', (request, response) => {
    
    // Set the response header   Set allow cross domain 
    response.setHeader('Access-Control-Allow-Origin', '*');
    response.setHeader('Access-Control-Allow-Headers', '*');
    // response.send('Hello jQuery AJAX');
    const data = {
    name:' Silicon Valley '};
    response.send(JSON.stringify(data));
});

//fetch  service 
app.all('/fetch-server', (request, response) => {
    
    // Set the response header   Set allow cross domain 
    response.setHeader('Access-Control-Allow-Origin', '*');
    response.setHeader('Access-Control-Allow-Headers', '*');
    // response.send('Hello jQuery AJAX');
    const data = {
    name:' Silicon Valley '};
    response.send(JSON.stringify(data));
});

//jsonp service 
app.all('/jsonp-server',(request, response) => {
    
    // response.send('console.log("hello jsonp")');
    const data = {
    
        name: ' Silicon Valley atguigu'
    };
    // Convert data to a string 
    let str = JSON.stringify(data);
    // Return results 
    response.end(`handle(${
      str})`);
});

// User name detection exists 
app.all('/check-username',(request, response) => {
    
    // response.send('console.log("hello jsonp")');
    const data = {
    
        exist: 1,
        msg: ' The user name already exists '
    };
    // Convert data to a string 
    let str = JSON.stringify(data);
    // Return results 
    response.end(`handle(${
      str})`);
});

//
app.all('/jquery-jsonp-server',(request, response) => {
    
    // response.send('console.log("hello jsonp")');
    const data = {
    
        name:' Silicon Valley ',
        city: [' Beijing ',' Shanghai ',' Shenzhen ']
    };
    // Convert data to a string 
    let str = JSON.stringify(data);
    // receive  callback  Parameters 
    let cb = request.query.callback;

    // Return results 
    response.end(`${
      cb}(${
      str})`);
});

app.all('/cors-server', (request, response)=>{
    
    // Set the response header 
    response.setHeader("Access-Control-Allow-Origin", "*");
    response.setHeader("Access-Control-Allow-Headers", '*');
    response.setHeader("Access-Control-Allow-Method", '*');
    // response.setHeader("Access-Control-Allow-Origin", "http://127.0.0.1:5500");
    response.send('hello CORS');
});

//4.  Listening port starts service 
app.listen(8000, () => {
    
    console.log(" Service started , 8000  Port monitoring ....");
});

Web Socket

Web Socket（ Socket ） The goal is to achieve full duplex with the server through a long-term connection 、 Two way communication . stay JavaScript

Created in Web Socket when , One HTTP The request is sent to the server to initialize the connection . After the server responds , Connection to use HTTP

Of Upgrade Head from HTTP The protocol switches to Web Socket agreement . It means Web Socket Can't pass the standard HTTP service

Implementation of the processor , Instead, you must use a proprietary server that supports the protocol .

because Web Socket Using custom protocol , therefore URL programme （scheme） There was a slight change ： No more use http:// or https://,

And you want to use ws:// and wss://. The former is an insecure connection , The latter is secure connection . In the specified Web Socket URL when , Must pack

contain URL programme , Because it is possible to support other schemes in the future .

Use custom protocols instead of HTTP The benefits of the agreement are , Very little data can be sent between the client and the server , It won't be right

HTTP Cause any burden . Use smaller packets to make Web Socket It is very suitable for mobile applications with obvious bandwidth and delay problems .

The disadvantages of using custom protocols are , Defining an agreement takes longer than defining JavaScript API longer .Web Socket I got all the mainstream

Browser support 

//  establish WebSocket
let socket = new WebSocket("ws://www.example.com/server.php");

// readyState  Property indicates the current state .
// - WebSocket.OPENING（0）： Connection is being established .
// - WebSocket.OPEN（1）： Connection established .
// - WebSocket.CLOSING（2）： The connection is closing .
// - WebSocket.CLOSE（3）： Connection closed .

//  send data 
let stringData = "Hello world!";  //  character string 
let arrayBufferData = Uint8Array.from(['f', 'o', 'o']); // ArrayBuffe
let blobData = new Blob(['f', 'o', 'o']); // Blob
socket.send(stringData); 
socket.send(arrayBufferData.buffer); 
socket.send(blobData);

//  Receive data 
socket.onmessage = function(event) {
     
  let data = event.data; 
  //  Perform some operations on the data 
};

//  Triggered when the connection is successfully established 
socket.onopen = function() {
     
  alert("Connection established."); 
}; 

//  Trigger... When an error occurs . The connection cannot survive 
socket.onerror = function() {
     
  alert("Connection error."); 
}; 

//  Trigger... When the connection is closed 
socket.onclose = function() {
     
  alert("Connection closed."); 
};
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