JavaScript XHR, buscar

1 método de solicitud de datos de front-end

2 Análisis del protocolo HTTP

3 Uso básico de XHR

Avance y empaquetado de 4 XHR

5 Explicación detallada del uso de Fetch

6 Proceso de carga de archivos front-end

Todas las primeras páginas se realizaron en el back-end y el navegador obtuvo directamente la visualización de la página, utilizando jsp, asp, php y otros idiomas. Esto se denomina SSR de renderizado del lado del servidor.

Aquí, el backend envía datos al frontend, y los datos dan como resultado que el frontend represente la página, lo que se denomina representación del lado del cliente.

Tutorial del complemento FeHelper

1

 const banners = {
      "banner": {
        "context": {
          "currentTime": 1538014774
        },
        "isEnd": true,
        "list": [
          {
            "acm": "3.mce.2_10_1jhwa.43542.0.ccy5br4OlfK0Q.pos_0-m_454801-sd_119",
            "height": 390,
            "height923": 390,
            "image": "https://s10.mogucdn.com/mlcdn/c45406/180926_45fkj8ifdj4l824l42dgf9hd0h495_750x390.jpg",
            "image923": "https://s10.mogucdn.com/mlcdn/c45406/180926_7d5c521e0aa3h38786lkakebkjlh8_750x390.jpg",
            "link": "https://act.mogujie.com/huanxin0001?acm=3.mce.2_10_1jhwa.43542.0.ccy5br4OlfK0Q.pos_0-m_454801-sd_119",
            "title": "焕新女装节",
            "width": 750,
            "width923": 750
          },
          {
            "acm": "3.mce.2_10_1ji16.43542.0.ccy5br4OlfK0R.pos_1-m_454889-sd_119",
            "height": 390,
            "height923": 390,
            "image": "https://s10.mogucdn.com/mlcdn/c45406/180926_31eb9h75jc217k7iej24i2dd0jba3_750x390.jpg",
            "image923": "https://s10.mogucdn.com/mlcdn/c45406/180926_14l41d2ekghbeh771g3ghgll54224_750x390.jpg",
            "link": "https://act.mogujie.com/ruqiu00001?acm=3.mce.2_10_1ji16.43542.0.ccy5br4OlfK0R.pos_1-m_454889-sd_119",
            "title": "入秋穿搭指南",
            "width": 750,
            "width923": 750
          },
          {
            "acm": "3.mce.2_10_1jfj8.43542.0.ccy5br4OlfK0S.pos_2-m_453270-sd_119",
            "height": 390,
            "height923": 390,
            "image": "https://s10.mogucdn.com/mlcdn/c45406/180919_3f62ijgkj656k2lj03dh0di4iflea_750x390.jpg",
            "image923": "https://s10.mogucdn.com/mlcdn/c45406/180919_47iclhel8f4ld06hid21he98i93fc_750x390.jpg",
            "link": "https://act.mogujie.com/huanji001?acm=3.mce.2_10_1jfj8.43542.0.ccy5br4OlfK0S.pos_2-m_453270-sd_119",
            "title": "秋季护肤大作战",
            "width": 750,
            "width923": 750
          },
          {
            "acm": "3.mce.2_10_1jepe.43542.0.ccy5br4OlfK0T.pos_3-m_452733-sd_119",
            "height": 390,
            "height923": 390,
            "image": "https://s10.mogucdn.com/mlcdn/c45406/180917_18l981g6clk33fbl3833ja357aaa0_750x390.jpg",
            "image923": "https://s10.mogucdn.com/mlcdn/c45406/180917_0hgle1e2c350a57ekhbj4f10a6b03_750x390.jpg",
            "link": "https://act.mogujie.com/liuxing00001?acm=3.mce.2_10_1jepe.43542.0.ccy5br4OlfK0T.pos_3-m_452733-sd_119",
            "title": "流行抢先一步",
            "width": 750,
            "width923": 750
          }
        ],
        "nextPage": 1
      }
    }

Uso básico de la solicitud XHR-XHR

1

 // 1.创建XMLHttpRequest对象
    const xhr = new XMLHttpRequest()

    // 2.监听状态的改变(宏任务)
    xhr.onreadystatechange = function() {
      // console.log(xhr.response)
      if (xhr.readyState !== XMLHttpRequest.DONE) return

      // 将字符串转成JSON对象(js对象)
      const resJSON = JSON.parse(xhr.response)
      const banners = resJSON.data.banner.list
      console.log(banners)
    }

    // 3.配置请求open
    // method: 请求的方式(get/post/delete/put/patch...)
    // url: 请求的地址
    xhr.open("get", "http://123.207.32.32:8000/home/multidata")

    // 4.发送请求(浏览器帮助发送对应请求)
    xhr.send()

Monitoreo de cambios de estado XHR-XHR

Lo que se envía aquí es una solicitud asincrónica y se puede obtener el código de estado, los 4 códigos de estado corresponden a diferentes eventos.

 // 1.创建XMLHttpRequest对象
    const xhr = new XMLHttpRequest()

    // 2.监听状态的改变(宏任务)
    // 监听四种状态
    xhr.onreadystatechange = function() {
      // 1.如果状态不是DONE状态, 直接返回
      if (xhr.readyState !== XMLHttpRequest.DONE) return

      // 2.确定拿到了数据
      console.log(xhr.response)
    }

    // 3.配置请求open
    xhr.open("get", "http://123.207.32.32:8000/home/multidata")

    // 4.发送请求(浏览器帮助发送对应请求)
    xhr.send()

XHR: XHR envía una solicitud sincrónica

---

El tercer parámetro de apertura puede establecer si es una solicitud asincrónica. Configurar falso lo cambiará a una solicitud sincrónica. Solo cuando el servidor regrese al navegador y lo acepte se ejecutará el código posterior.

 // 1.创建XMLHttpRequest对象
    const xhr = new XMLHttpRequest()

    // 2.监听状态的改变(宏任务)
    // 监听四种状态
    // xhr.onreadystatechange = function() {
    //   // 1.如果状态不是DONE状态, 直接返回
    //   if (xhr.readyState !== XMLHttpRequest.DONE) return

    //   // 2.确定拿到了数据
    //   console.log(xhr.response)
    // }

    // 3.配置请求open
    // async: false
    // 实际开发中要使用异步请求, 异步请求不会阻塞js代码继续执行
    xhr.open("get", "http://123.207.32.32:8000/home/multidata", false)

    // 4.发送请求(浏览器帮助发送对应请求)
    xhr.send()

    // 5.同步必须等到有结果后, 才会继续执行
    console.log(xhr.response)

    console.log("------")
    console.log("++++++")
    console.log("******")

Escuchando otros eventos de XHR-XHR

Las funciones se llaman de manera diferente.

   const xhr = new XMLHttpRequest()
    // onload监听数据加载完成
    xhr.onload = function() {
      console.log("onload")
    }
    xhr.open("get", "http://123.207.32.32:8000/home/multidata")
    xhr.send()

XHR: datos y tipo de respuesta XHR

Informar a xhr del tipo de datos obtenidos
    xhr.responseType = "json"

    // 1.
    const xhr = new XMLHttpRequest()

    // 2.onload监听数据加载完成
    xhr.onload = function() {
      // const resJSON = JSON.parse(xhr.response)
      console.log(xhr.response)
      // console.log(xhr.responseText)
      // console.log(xhr.responseXML)
    }

    // 3.告知xhr获取到的数据的类型
    xhr.responseType = "json"
    // xhr.responseType = "xml"

    // 4.配置网络请求
    // 4.1.json类型的接口
    xhr.open("get", "http://123.207.32.32:8000/home/multidata")
    // 4.2.json类型的接口
    // xhr.open("get", "http://123.207.32.32:1888/01_basic/hello_json")
    // 4.3.text类型的接口
    // xhr.open("get", "http://123.207.32.32:1888/01_basic/hello_text")
    // 4.4.xml类型的接口
    // xhr.open("get", "http://123.207.32.32:1888/01_basic/hello_xml")

    // 5.发送网络请求
    xhr.send()

XHR: obtenga el código de estado de HTTP

estado.xhr

 // 1.创建对象
    const xhr = new XMLHttpRequest()

    // 2.监听结果
    xhr.onload = function() {
      console.log(xhr.status, xhr.statusText)
      // 根据http的状态码判断是否请求成功
      if (xhr.status >= 200 && xhr.status < 300) {
        console.log(xhr.response)
      } else {
        console.log(xhr.status, xhr.statusText)
      }
    }

    xhr.onerror = function() {
      console.log("onerror", xhr.status, xhr.statusText)
    }

    // 3.设置响应类型
    xhr.responseType = "json"

    // 4.配置网络请求
    // xhr.open("get", "http://123.207.32.32:8000/abc/cba/aaa")
    xhr.open("get", "http://123.207.32.32:8000/home/multidata")

    // 5.发送网络请求
    xhr.send()

Parámetros de solicitud XHR-GET-POST

1

 const formEl = document.querySelector(".info")
    const sendBtn = document.querySelector(".send")
    sendBtn.onclick = function() {
      // 创建xhr对象
      const xhr = new XMLHttpRequest()

      // 监听数据响应
      xhr.onload = function() {
        console.log(xhr.response)
      }

      // 配置请求
      xhr.responseType = "json"

      // 1.传递参数方式一: get -> query
      // xhr.open("get", "http://123.207.32.32:1888/02_param/get?name=why&age=18&address=广州市")

      // 2.传递参数方式二: post -> urlencoded
      // xhr.open("post", "http://123.207.32.32:1888/02_param/posturl")
      // // 发送请求(请求体body)
      // xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded")
      // xhr.send("name=why&age=18&address=广州市")

      // 3.传递参数方式三: post -> formdata
      // xhr.open("post", "http://123.207.32.32:1888/02_param/postform")
      // // formElement对象转成FormData对象
      // const formData = new FormData(formEl)
      // xhr.send(formData)

      // 4.传递参数方式四: post -> json
      xhr.open("post", "http://123.207.32.32:1888/02_param/postjson")
      xhr.setRequestHeader("Content-type", "application/json")
      xhr.send(JSON.stringify({name: "why", age: 18, height: 1.88}))
    }

Encapsulación de solicitudes de red XHR-Ajax

1

 // 练习hyajax -> axios
    function hyajax({
      url,
      method = "get",
      data = {},
      headers = {}, // token
      success,
      failure
    } = {}) {
      // 1.创建对象
      const xhr = new XMLHttpRequest()

      // 2.监听数据
      xhr.onload = function() {
        if (xhr.status >= 200 && xhr.status < 300) {
          success && success(xhr.response)
        } else {
          failure && failure({ status: xhr.status, message: xhr.statusText })
        }
      }

      // 3.设置类型
      xhr.responseType = "json"

      // 4.open方法
      if (method.toUpperCase() === "GET") {
        const queryStrings = []
        for (const key in data) {
          queryStrings.push(`${key}=${data[key]}`)
        }
        url = url + "?" + queryStrings.join("&")
        xhr.open(method, url)
        xhr.send()
      } else {
        xhr.open(method, url)
        xhr.setRequestHeader("Content-type", "application/json")
        xhr.send(JSON.stringify(data))
      }

      return xhr
    }

    // 调用者
    hyajax({
      url: "http://123.207.32.32:1888/02_param/get",
      method: "GET",
      data: {
        name: "why",
        age: 18
      },
      success: function(res) {
        console.log("res:", res)
      },
      failure: function(err) {
        // alert(err.message)
      }
    })

    // hyajax({
    //   url: "http://123.207.32.32:1888/02_param/postjson",
    //   method: "post",
    //   data: {
    //     name: "jsondata",
    //     age: 22
    //   },
    //   success: function(res) {
    //     console.log("res:", res)
    //   },
    //   failure: function(err) {
    //     // alert(err.message)
    //   }
    // })

Herramienta de solicitud de red XHR-Ajax

hyajax_promise.js

// 练习hyajax -> axios
function hyajax({
  url,
  method = "get",
  data = {},
  timeout = 10000,
  headers = {}, // token
} = {}) {
  // 1.创建对象
  const xhr = new XMLHttpRequest()

  // 2.创建Promise
  const promise = new Promise((resolve, reject) => {

    // 2.监听数据
    xhr.onload = function() {
      if (xhr.status >= 200 && xhr.status < 300) {
        resolve(xhr.response)
      } else {
        reject({ status: xhr.status, message: xhr.statusText })
      }
    }

    // 3.设置类型
    xhr.responseType = "json"
    xhr.timeout = timeout

    // 4.open方法
    if (method.toUpperCase() === "GET") {
      const queryStrings = []
      for (const key in data) {
        queryStrings.push(`${key}=${data[key]}`)
      }
      url = url + "?" + queryStrings.join("&")
      xhr.open(method, url)
      xhr.send()
    } else {
      xhr.open(method, url)
      xhr.setRequestHeader("Content-type", "application/json")
      xhr.send(JSON.stringify(data))
    }
  })

  promise.xhr = xhr

  return promise
}

hyajax.js

// 练习hyajax -> axios
function hyajax({
  url,
  method = "get",
  data = {},
  timeout = 10000,
  headers = {}, // token
  success,
  failure
} = {}) {
  // 1.创建对象
  const xhr = new XMLHttpRequest()

  // 2.监听数据
  xhr.onload = function() {
    if (xhr.status >= 200 && xhr.status < 300) {
      success && success(xhr.response)
    } else {
      failure && failure({ status: xhr.status, message: xhr.statusText })
    }
  }

  // 3.设置类型
  xhr.responseType = "json"
  xhr.timeout = timeout

  // 4.open方法
  if (method.toUpperCase() === "GET") {
    const queryStrings = []
    for (const key in data) {
      queryStrings.push(`${key}=${data[key]}`)
    }
    url = url + "?" + queryStrings.join("&")
    xhr.open(method, url)
    xhr.send()
  } else {
    xhr.open(method, url)
    xhr.setRequestHeader("Content-type", "application/json")
    xhr.send(JSON.stringify(data))
  }

  return xhr
}

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  
  <!-- <script src="./utils/hyajax.js"></script> -->
  <script src="./utils/hyajax_promise.js"></script>
  <script>
    const promise = hyajax({
      url: "http://123.207.32.32:1888/02_param/get",
      data: {
        username: "coderwhy",
        password: "123456"
      }
    })

    promise.then(res => {
      console.log("res:", res)
    }).catch(err => {
      console.log("err:", err)
    })
  </script>
</body>
</html>

Solicitud de cancelación de tiempo de espera XHR

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  
  <button>取消请求</button>

  <script>
    const xhr = new XMLHttpRequest()

    xhr.onload = function() {
      console.log(xhr.response)
    }
    xhr.onabort = function() {
      console.log("请求被取消掉了")
    }
    
    xhr.responseType = "json"

    // 1.超市时间的设置
    xhr.ontimeout = function() {
      console.log("请求过期: timeout")
    }
    // timeout: 浏览器达到过期时间还没有获取到对应的结果时, 取消本次请求
    // xhr.timeout = 3000
    xhr.open("get", "http://123.207.32.32:1888/01_basic/timeout")

    xhr.send()

    // 2.手动取消结果
    const cancelBtn = document.querySelector("button")
    cancelBtn.onclick = function() {
      xhr.abort()
    }

  </script>

</body>
</html>

Uso básico de la función Fetch-Fetch

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  
  <script>

    // 1.fetch发送get请求
    // 1.1.未优化的代码
    // fetch("http://123.207.32.32:8000/home/multidata").then(res => {
    //   // 1.获取到response
    //   const response = res

    //   // 2.获取具体的结果
    //   response.json().then(res => {
    //     console.log("res:", res)
    //   })
    // }).catch(err => {
    //   console.log("err:", err)
    // })

    // 1.2. 优化方式一:
    // fetch("http://123.207.32.32:8000/home/multidata").then(res => {
    //   // 1.获取到response
    //   const response = res
    //   // 2.获取具体的结果
    //   return response.json()
    // }).then(res => {
    //   console.log("res:", res)
    // }).catch(err => {
    //   console.log("err:", err)
    // })

    // 1.3. 优化方式二:
    // async function getData() {
    //   const response = await fetch("http://123.207.32.32:8000/home/multidata")
    //   const res = await response.json()
    //   console.log("res:", res)
    // }
    // getData()


    // 2.post请求并且有参数
    async function getData() {
      // const response = await fetch("http://123.207.32.32:1888/02_param/postjson", {
      //   method: "post",
      //   // headers: {
      //   //   "Content-type": "application/json"
      //   // },
      //   body: JSON.stringify({
      //     name: "why",
      //     age: 18
      //   })
      // })
      
      const formData = new FormData()
      formData.append("name", "why")
      formData.append("age", 18)
      const response = await fetch("http://123.207.32.32:1888/02_param/postform", {
        method: "post",
        body: formData
      })

      // 获取response状态
      console.log(response.ok, response.status, response.statusText)

      const res = await response.json()
      console.log("res:", res)
    }
    getData()

  </script>

</body>
</html>

Tutorial de la interfaz de carga de archivos XHR

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>

  <input class="file" type="file">
  <button class="upload">上传文件</button>
  
  <script>

    // xhr/fetch

    const uploadBtn = document.querySelector(".upload")
    uploadBtn.onclick = function() {
      // 1.创建对象
      const xhr = new XMLHttpRequest()

      // 2.监听结果
      xhr.onload = function() {
        console.log(xhr.response)
      }

      xhr.onprogress = function(event) {
        console.log(event)
      }
      

      xhr.responseType = "json"
      xhr.open("post", "http://123.207.32.32:1888/02_param/upload")

      // 表单
      const fileEl = document.querySelector(".file")
      const file = fileEl.files[0]

      const formData = new FormData()
      formData.append("avatar", file)

      xhr.send(formData)
    }
  </script>

</body>
</html>

Tutorial de la interfaz de carga de archivos

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>

  <input class="file" type="file">
  <button class="upload">上传文件</button>
  
  <script>

    // xhr/fetch

    const uploadBtn = document.querySelector(".upload")
    uploadBtn.onclick = async function() {
      // 表单
      const fileEl = document.querySelector(".file")
      const file = fileEl.files[0]

      const formData = new FormData()
      formData.append("avatar", file)

      // 发送fetch请求
      const response = await fetch("http://123.207.32.32:1888/02_param/upload", {
        method: "post",
        body: formData
      })
      const res = await response.json()
      console.log("res:", res)
    }

  </script>

</body>
</html>