19.Map.html 1.4 KB

12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455
  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. /**
  11. * Map() 类似于对象 键值对中的对象
  12. * 可以使用扩展运算符 for..of
  13. * size 返回键值对中的元素个数
  14. * set() 往集合中添加键值对
  15. * get() 获取集合中的键值
  16. * has() 查找Map集合中是否包含所要查找的属性 返回值为布尔值
  17. * clear() 清空集合中的所有值 返回undefined
  18. *
  19. */
  20. let s1 = new Map();
  21. console.log(s1,'s1');
  22. let s2 = new Map([
  23. ["name","Lucy"],
  24. ["age","18"],
  25. ["address","哈尔滨"]
  26. ]);
  27. console.log(s2,'s2');
  28. console.log(s2.size);
  29. s2.set("sex","女")
  30. console.log(s2);
  31. console.log(s2.get("name"));
  32. console.log(s2.has("age"));
  33. s2.clear();
  34. console.log(s2.clear());
  35. console.log(s2);
  36. var arr = [1,2,3,4,5,6];
  37. arr.map((ele,index)=>{
  38. console.log(ele,'值');
  39. console.log(index,'下标');
  40. })
  41. var arr2 = new Map();
  42. arr2.set("color","red");
  43. arr2.set("school","US");
  44. console.log(arr2);
  45. for(a of arr2.entries()) {
  46. console.log(a,'1');
  47. }
  48. // console.log(arr2.entries());
  49. </script>
  50. </body>
  51. </html>