15_symbol.html 866 B

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  1. <!DOCTYPE html>
  2. <html lang="en">
  3. <head>
  4. <meta charset="UTF-8">
  5. <meta name="viewport" content="width=device-width, initial-scale=1.0">
  6. <title>Document</title>
  7. </head>
  8. <body>
  9. <script>
  10. let obj = {
  11. userName:"张三",
  12. age:18
  13. }
  14. obj.sex = "男";
  15. // 对象中属性名是唯一且不允许重复的
  16. obj.age = 20;
  17. // symbol 类型表示唯一的,不能重复
  18. let sym = Symbol("sym");
  19. let sym2 = Symbol("sym");
  20. let sym3 = Symbol();
  21. obj[sym] = "hello";
  22. obj[sym2] = "world";
  23. obj[sym3] = "你好";
  24. // console.log(obj);
  25. // console.log(obj[sym]);
  26. // 遍历对象属性 如果是symbol类型,则不会遍历到
  27. for(let key in obj){
  28. console.log(key);
  29. }
  30. </script>
  31. </body>
  32. </html>