無法將未定義或空值轉換為對象的錯誤

Question

我最近在這里無法啟動代碼，導致無法將undefined或null轉換為object導致錯誤：

Utils.getCardsInSets((ERR, DATA) => {
    if (!ERR) {
        allCards = DATA;
        console.log("Card data loaded. [" + Object.keys(DATA).length + "]");
    } else {
        console.log("An error occurred while getting cards: " + ERR);
    }
});

控制台上顯示的錯誤

console.log("Card data loaded. [" + Object.keys(DATA).length + "]");
                                                   ^

TypeError: Cannot convert undefined or null to object
    at Function.keys (<anonymous>)
    at Utils.getCardsInSets (/root/test/index.js:37:52)
    at Request.request [as _callback] (/root/test/utils.js:41:13)
    at Request.self.callback (/root/test/node_modules/request/request.js:186:22)
    at emitTwo (events.js:125:13)
    at Request.emit (events.js:213:7)
    at Request.<anonymous> (/root/test/node_modules/request/request.js:1163:10)
    at emitOne (events.js:115:13)
    at Request.emit (events.js:210:7)
    at IncomingMessage.<anonymous> (/root/test/node_modules/request/request.js:1085:12)

Answer 1

您的Utils.getCardsInSets返回undefined或null DATA 。 在上面的代碼中，您沒有將任何查詢參數傳遞給該方法，請檢查是否需要傳遞任何參數。

如果所做的一切正確，則方法將根據特定條件返回undefined/null 。 只需檢查DATA然后確定其密鑰長度即可。

Utils.getCardsInSets((ERR, DATA) => {
    if (!ERR) {
        allCards = DATA;
        var datalength = (!!DATA) ? Object.keys(DATA).length : 0;
        console.log("Card data loaded. [" + datalength  + "]");
    } else {
        console.log("An error occurred while getting cards: " + ERR);
    }
});