2つのMapオブジェクトが等しいかどうかを確認するにはどうすればよいですか？

"use strict";

function compareMaps(map1, map2) {
    var testVal;
    if (map1.size !== map2.size) {
        return false;
    }
    for (var [key, val] of map1) {
        testVal = map2.get(key);
        // in cases of an undefined value, make sure the key
        // actually exists on the object so there are no false positives
        if (testVal !== val || (testVal === undefined && !map2.has(key))) {
            return false;
        }
    }
    return true;
}

// construct two maps that are initially identical
var o = {"k" : 2}

var m1 = new Map();
m1.set("obj", o);
m1.set("str0", undefined);
m1.set("str1", 1);
m1.set("str2", 2);
m1.set("str3", 3);

var m2 = new Map();
m2.set("str0", undefined);
m2.set("obj", o);
m2.set("str1", 1);
m2.set("str2", 2);
m2.set("str3", 3);

log(compareMaps(m1, m2));

// add an undefined key to m1 and a corresponding other key to m2
// this will pass the .size test and even pass the equality test, but not pass the
// special test for undefined values
m1.set("str-undefined", undefined);
m2.set("str4", 4);
log(compareMaps(m1, m2));

// remove one key from m1 so m2 has an extra key
m1.delete("str-undefined");
log(compareMaps(m1, m2));

// add that same extra key to m1, but give it a different value
m1.set("str4", 5);
log(compareMaps(m1, m2));

function log(args) {
    var str = "";
    for (var i = 0; i < arguments.length; i++) {
        if (typeof arguments[i] === "object") {
            str += JSON.stringify(arguments[i]);
        } else {
            str += arguments[i];
        }
    }
    var div = document.createElement("div");
    div.innerHTML = str;
    var target = log.id ? document.getElementById(log.id) : document.body;
    target.appendChild(div);
}