练习

2021-04-29 17:16:40 +08:00
parent 812be57880
commit 55c598cdb1
195 changed files with 12788 additions and 34 deletions
--- a/teaching/jwl/课件/es6/promise.html
+++ b/teaching/jwl/课件/es6/promise.html
@@ -0,0 +1,86 @@
+<!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>
+    <script>
+        console.log("创建proimise之前")
+        var promiseobj=new Promise((resolve,reject)=>{
+            console.log("创建promise")
+            if (this.readyState !== 4) {
+                return;
+            } 
+            if (this.status === 200) {
+                cosnole.log("mysuccess")
+                resolve(this.response);
+            } else {
+                console.log("myerror")
+                reject(new Error(this.statusText));
+            }
+        })
+        promiseobj.then(()=>{
+            console.log("success")
+            
+        })
+        console.log("promise成功之后")
+
+
+        // readyState
+        // 用promise封装ajax 
+        const getJSON = function(url) {
+        const promise = new Promise(function(resolve, reject){
+            const handler = function() {
+            console.log(this.readyState)
+            console.log(this.status)
+            if (this.readyState !== 4) {
+                return;
+            }
+            if (this.status === 200) {
+                resolve(this.response);
+            } else {
+                reject(new Error(this.statusText));
+            }
+            };
+            const client = new XMLHttpRequest();
+            client.open("GET", url);
+            client.onreadystatechange = handler;
+            client.responseType = "json";
+            client.setRequestHeader("Accept", "application/json");
+            client.send();
+
+        });
+
+        return promise;
+        };
+
+
+        //  readystate 的五种状态
+        // 0 － （未初始化）还没有调用send()方法
+        // 1 － （载入）已调用send()方法，正在发送请求
+        // 2 － （载入完成）send()方法执行完成，已经接收到全部响应内容
+        // 3 － （交互）正在解析响应内容
+        // 4 － （完成）响应内容解析完成，可以在客户端调用了
+
+
+
+        getJSON("/posts.json").then(function(json) {
+        console.log('Contents: ' + json);
+        }, function(error) {
+        console.error('出错了', error);
+        });
+
+        async function login(){
+           http("./login.php").then((res)=>{
+               console.log(res)
+           })
+            var res=http("./login.php")
+        }
+
+    </script>
+</head>
+<body>
+    
+</body>
+</html>