如何訪問括號符號中的對象鍵？

Question

我似乎無法弄清楚如何使用括號表示法訪問spearguns對象。 我正在嘗試訪問“ heft”鍵。 控制台日志說“未定義”。 任何幫助將是巨大的，謝謝。

var rockSpearguns = {
  Sharpshooter: {barbs: 2, weight: 10, heft: "overhand"},
  Pokepistol: {barbs: 4, weight: 8, heft: "shoulder"},
  Javelinjet: {barbs: 4, weight: 12, heft: "waist"},
  Firefork: {barbs: 6, weight: 8, heft: "overhand"},
  "The Impaler": {barbs: 1, weight: 30, heft: "chest"}
};

function listGuns(guns) {
  for (var speargun in guns) {
    // modify the log message here
    console.log("Behold! " + speargun + ", with " + this["heft"] + " heft!");
  }
}

listGuns(rockSpearguns);

Answer 1

您需要從屬性名稱中獲得對槍的引用，如下所示：

var rockSpearguns = {
                Sharpshooter: {barbs: 2, weight: 10, heft: "overhand"},
                Pokepistol: {barbs: 4, weight: 8, heft: "shoulder"},
                Javelinjet: {barbs: 4, weight: 12, heft: "waist"},
                Firefork: {barbs: 6, weight: 8, heft: "overhand"},
                "The Impaler": {barbs: 1, weight: 30, heft: "chest"}
};

function listGuns(guns) {
    for (var speargun in guns) {
        // modify the log message here
        var gun = guns[speargun];
        console.log("Behold! " + speargun + ", with " + gun["heft"] + " heft!");
    }
}

Answer 2

這是我最終使用的內容：

function listGuns(guns) {
  for (var speargun in guns) {
    // modify the log message here

    console.log("Behold! " + speargun + ", with " + guns[speargun]["heft"] + " heft!");
  }