<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>新型数据结构Map应用</title> </head> <body> </body> <script> // 1、 // let num = 123; // let arr =[1,2,3]; // let fun = function () {}; // let obj = {}; // const map1 = new Map(); // map1.set(num,"q1"), // map1.set(arr,"q2"); // map1.set(fun,"q3"); // map1.set(obj,"q4"); // console.log(map1); // console.log(map1.keys()); // for (const key of map1.keys()) { // console.log(key); // } // 2、 const map2 = new Map([ ["a1","1"], ["a2","2"], ["a3","3"] ]); map2.set("a4","4"); map2.delete("a2"); console.log(map2.has("a2"));//false console.log(map2); let arr1 = [...map2.values()];//可以把所有的value转存到数组 console.log(arr1); let arr2 = [...map2.keys()];//可以把所有的key转存到数组 console.log(arr2); let arr3 = [...map2.entries()];//显示数组里面的所有内容 console.log(arr3); for (const key of map2.keys()) { console.log(key); } // 适用于集合类型 </script> </html>