js 0.0

2021-01-28 09:06:45 +08:00
parent f230cfc37f
commit 5d39890424
18 changed files with 1380 additions and 0 deletions
--- a/js/demo/day1.html
+++ b/js/demo/day1.html
@@ -0,0 +1,46 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+    <script>
+        var lanzi="苹果"
+        // var lanzi   ---第一步  变量声明 问系统要个篮子 用来放东西   
+        // lanzi="苹果"  --第二步  赋值  把苹果放到篮子里
+        document.write('明世隐')
+
+        var a=1,b=2,c=3,d=4,e;      // 声明多个变量
+        document.write(a,b,c,d,e)
+
+        var no=1;
+        var num=no
+        num=3;
+        console.log(no,num)
+
+        var obj={name:'蔡文姬',age:20}
+        var obj1=obj
+        obj1.name='明世隐'
+        console.log(obj)
+        console.log(obj1)
+
+
+        //检测数据类型
+        console.log(typeof "king")
+        console.log(typeof obj) //object
+        console.log(typeof [1,2,3])  //array--> object
+        console.log(typeof function(){})  //object
+
+        console.log(Number('2AAAAA'))  //NAN
+        console.log(Number('2'))    //2
+
+        console.log('2aaaaa'+4) //2aaaaa4
+        console.log("4"+4)  //44
+        console.log("4"-4)   //0
+        console.log(true+5)  //6
+    </script>
+</head>
+<body>
+    
+</body>
+</html>