為了我自己的利益，我正在瀏覽 Javascript 中的每個內置結構化對象，特別是我正在嘗試每個基本的“for”循環，以便我了解什么在哪里工作。就 Map 而言，我注意到 for/in 循環是靜默的。我希望它返回映射中每個條目的鍵值。let map = new Map([[1, 1], ["two", "two"]]);map.set("three", 3); // Instead of addconsole.log(`map has three = ${map.has("three")}`);console.log(`map has size ${map.size}`);// no 'for loop' because map uses keys instead of index numbersfor (let key in map) console.log(`for key ${key} in map ${map}`); // <<< This does not return??for (let value of map) console.log(`for ${value} of ${map}`); map.forEach((value, key, localScopeCopyOfMap) => console.log(`forEach value ${value} in map ${[...localScopeCopyOfMap]}`));為什么這不返回任何內容？