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JS第1课-JavaScript基础-九期线上班
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  1. 1、javascript变量、函数的定义
  2. 2、javascript流程控制if else switch
  3. 3、javascript三种循环
  4. 4、数据类型转换：parseInt、isNaN函数的使用
  1. <!DOCTYPE html>
  2. <html lang="en">
  3. <head>
  4.     <meta charset="UTF-8">
  5.     <title>Title</title>
  6. </head>
  7. <body>
  8. <input type="text" id="age" placeholder="请输入您的年龄">
  9. <button onclick="save()">提交</button>
  11. <!--script-->
  12. <script>
  14. /***************变量定义 var **********/
  15.     var age = 1;
  16.     var name = "jason";
  17.     var newFloat = 1.1;
  19. /***************函数**********/
  20.     //函数的定义
  21.     function func1() {
  22.         //控制台输出
  23.         console.log("哈哈哈");
  24.     }
  26.     function func2(name) {
  27.         console.log(name);
  28.     }
  30.     function func3(age) {
  31.         return age+1;
  32.     }
  34.     //调用函数
  35.     func1();
  36.     func2('jack');
  37.     console.log(func3(1));
  39. /***************变量的作用域**********/
  40.     function func4(num1) {
  41.         var num = 5;
  42.         console.log(num);
  43.         return num + num1;
  44.     }
  45.     console.log(func4(age));
  46.     //使用全局函数
  47.     console.log(age);
  48.     //调用局部变量失败
  49.     // console.log(num);
  51. /***************流程控制**********/
  52.     var sore = 90;
  53.     function if1() {
  54.         //if
  55.         if (sore >80){
  56.             console.log("成绩优秀");
  57.         }
  58.     }
  60.     //if else
  61.     function if2() {
  62.         if (sore >= 60){
  63.             console.log("及格");
  64.         }else {
  65.             console.log("不及格");
  66.         }
  67.     }
  69.     //if elseif
  70.     function if3() {
  71.         if (sore >= 90){
  72.             console.log("优秀");
  73.         }else if (sore >= 80){
  74.             console.log("良好");
  75.         }else if (sore>=60){
  76.             console.log("及格");
  77.         }else {
  78.             console.log("不及格");
  79.         }
  80.     }
  82.     //switch 一般用于单值匹配
  83.     switch (sore) {
  84.         case 100:
  85.         case 90:
  86.             console.log("优秀");
  87.             break;
  88.         case 89:
  89.         case 70:
  90.             console.log("一般");
  91.             break;
  92.         case 69:
  93.         case 60:
  94.             console.log("及格");
  95.             break;
  96.         default:
  97.             console.log("不及格");
  98.     }
  100. /***************循环**********/
  101. function for1() {
  102.     for (var j = 0;j < 10; j++ ){
  103.         console.log(j);
  104.     }
  105. }
  107. function for2() {
  108.     var i = 0;
  109.     while (i < 5){
  110.         i++;
  111.         console.log(i);
  112.     }
  113. }
  115. function for3() {
  116.     var i = 5;
  117.     do {
  118.         i--;
  119.         console.log(i);
  120.     }while (i > 0)
  121. }
  123. /**********typeof、parseInt、isNaN函数的使用********/
  125. function typeofFunc() {
  126.     var intStr = 10;
  127.     if (typeof(intStr) == 'undefined' ){
  128.         alert("未定义");
  129.     }else {
  130.         alert(intStr+5);
  131.     }
  132. }
  134. function save() {
  135.     var age = document.getElementById('age').value;
  136.     //转换为int类型
  137.     age = parseInt(age);
  138.     if (age < 1 || age > 130){
  139.         alert("您输入的年龄不合法");
  140.     }
  141.     if (isNaN(age)){
  142.         alert("年龄不能为空,请重新输入");
  143.     }
  144. }
  146. </script>
  148. </body>
  149. </html>
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