javascript compare maps

1function listFruits() {
2  let fruits = ["apple", "cherry", "pear"]
3  
4  fruits.map((fruit, index) => {
5    console.log(index, fruit)
6  })
7}
8
9listFruits()
10
11// https://jsfiddle.net/tmoreland/16qfpkgb/3/

1const numbers = [0,1,2,3];
2
3console.log(numbers.map((number) => {
4  return number;
5}));

1"use strict";
2
3function compareMaps(map1, map2) {
4    var testVal;
5    if (map1.size !== map2.size) {
6        return false;
7    }
8    for (var [key, val] of map1) {
9        testVal = map2.get(key);
10        // in cases of an undefined value, make sure the key
11        // actually exists on the object so there are no false positives
12        if (testVal !== val || (testVal === undefined && !map2.has(key))) {
13            return false;
14        }
15    }
16    return true;
17}
18
19// construct two maps that are initially identical
20var o = {"k" : 2}
21
22var m1 = new Map();
23m1.set("obj", o);
24m1.set("str0", undefined);
25m1.set("str1", 1);
26m1.set("str2", 2);
27m1.set("str3", 3);
28
29var m2 = new Map();
30m2.set("str0", undefined);
31m2.set("obj", o);
32m2.set("str1", 1);
33m2.set("str2", 2);
34m2.set("str3", 3);
35
36log(compareMaps(m1, m2));
37
38// add an undefined key to m1 and a corresponding other key to m2
39// this will pass the .size test and even pass the equality test, but not pass the
40// special test for undefined values
41m1.set("str-undefined", undefined);
42m2.set("str4", 4);
43log(compareMaps(m1, m2));
44
45// remove one key from m1 so m2 has an extra key
46m1.delete("str-undefined");
47log(compareMaps(m1, m2));
48
49// add that same extra key to m1, but give it a different value
50m1.set("str4", 5);
51log(compareMaps(m1, m2));
52
53function log(args) {
54    var str = "";
55    for (var i = 0; i < arguments.length; i++) {
56        if (typeof arguments[i] === "object") {
57            str += JSON.stringify(arguments[i]);
58        } else {
59            str += arguments[i];
60        }
61    }
62    var div = document.createElement("div");
63    div.innerHTML = str;
64    var target = log.id ? document.getElementById(log.id) : document.body;
65    target.appendChild(div);
66}