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2021-06-03 10:52:41 +08:00
parent c5f18c6051
commit 907511778b
54 changed files with 3540 additions and 50 deletions
--- a/teaching/wanzhaoyi/js/shujuleixing.html
+++ b/teaching/wanzhaoyi/js/shujuleixing.html
@@ -0,0 +1,42 @@
+<!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>
+        // js 数据类型
+        // 基本数据类型 ：number string boolean undefined null
+        // 复杂数据类型: object 
+        // var arr=new Array()
+        // var fn=new Function()
+        // 基本数据类型和复杂数据类型的区别
+        // 检测数据类型
+        // 由低到高  typeof instanceof Object.prototype.tostring.call
+            // typeof   instanceof   Object.prototype.toString.call
+            var a=9
+            var type=Object.prototype.toString.call(a)
+            console.log(Object.prototype.toString.call([1,2,3,4]))
+            console.log(Object.prototype.toString.call(9),"mmmn")
+            console.log(type)
+            console.log(9 instanceof Number)
+            console.log(new Number(9) instanceof Number)
+            console.log([1,2,3,4] instanceof Array)
+            console.log(function fn(){} instanceof Function)
+            // instanceof  用法  被检测的值 instanceof 猜测的数据类型    
+            //             返回的是true/false
+
+            var key=123
+            console.log(typeof key)
+            console.log(typeof null)
+            console.log(typeof undefined)
+            console.log(typeof [4,3,1])
+            console.log(typeof function fm(){})
+
+    </script>
+</head>
+<body>
+    
+</body>
+</html>