22_symbl.html 637 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 num = Symbol();
  11. let num2 = Symbol();
  12. console.log(num);
  13. let obj = {
  14. userName:"张三",
  15. age:20
  16. }
  17. obj[num] = "李四";
  18. obj[num2] = "王五";
  19. obj.age = 18;
  20. console.log(obj);
  21. console.log(obj[num]);
  22. // Symbol不能被for in遍历
  23. for(let key in obj){
  24. console.log(key);
  25. }
  26. </script>
  27. </body>
  28. </html>