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javascript (常量、变量、函数)使用
秋闲独醉
Original
286 people have browsed it
  1. <!DOCTYPE html>
  2. <html lang="en">
  3. <head>
  4. <meta charset="UTF-8" />
  5. <meta http-equiv="X-UA-Compatible" content="IE=edge" />
  6. <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  7. <title>javascript基础</title>
  8. </head>
  9. <body>
  10. <!-- javascript代码可以被包含在<script></script>标签内,也可以包含在.js结尾的文件中 -->
  11. <!-- 第一种 -->
  12. <script>
  13. // js代码
  14. </script>
  15. <!-- 第二种 -->
  16. <!-- <script src="javascript.js"></script> -->
  17. <!-- javascript 变量的声名和定义 -->
  18. <script>
  19. // 变量名命名:必须只能有字母、数字、下划线、$,四种组合在一起;
  20. // 必须只能是字母、$、下划线开头。
  21. // 一般用小写字母。
  22. let a = "123";
  23. let a_ = "123";
  24. let _a = "123";
  25. let $_a = "123";
  26. let $_a1 = "123";
  27. // 以var 定义 的变量是全局变量,以let 定义的变里视作用域决定,可全局可局部
  28. {
  29. var b = "88";
  30. }
  31. {
  32. let c = "77";
  33. }
  34. console.log(b);
  35. // console.log(c); //这个报错,因为c是局部变量,不能在全局使用。
  36. // + 符号的使用,可以用作两个字符串之间的连接
  37. console.log("我是" + "一个好人");
  38. //常量的声名和赋值,都用同时,这个于变量不一样。
  39. //常量名通常是大写字母加下划线
  40. APP_NAME = "这是一个APP";
  41. console.log(APP_NAME);
  42. APP_NAME = "这不是一个APP";
  43. console.log(APP_NAME);
  44. //函数名通常用小驼峰命名
  45. let name = "佚名";
  46. function setUserName(param) {
  47. name = param;
  48. }
  49. setUserName("小丸子");
  50. console.log(name);
  51. //匿名函数
  52. let getUserName = function (username) {
  53. return "HELLO " + username;
  54. };
  55. console.log(getUserName("小不点"));
  56. let getUserName2 = (username) => {
  57. return "hello" + username;
  58. };
  59. console.log(getUserName2("小物件"));
  60. </script>
  61. </body>
  62. </html>
Correcting teacher:PHPzPHPz

Correction status:qualified

Teacher's comments:
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