else 语句不重新调整值

Question

在我的代码中，我正在检查window和window['cid_global']是否有任何一个未定义，

我想返回{brand: 'unknown', locale: {country: '', language: ''}, ENV: '', accessPath: '', contrastPreference: '' }到cid_global 。

但它返回为undefined 。

我在这里做错了什么？

stackBliz： https://stackblitz.com/edit/typescript-7d1urh

const isClient = typeof window;
const isCidGlobal = typeof window['cid_global'];

const _window = isClient !== undefined ? window : {};

const cid_global = (_window !== undefined && isCidGlobal !== undefined)? _window['cid_global'] : {brand: 'unknown', locale: {country: '', language: ''}, ENV: '', accessPath: '', contrastPreference: '' };

console.log(isCidGlobal) // undefined;
console.log(cid_global) // should return object instead of undefined;

Answer 1

typeof的结果是一个字符串。 您正在将它与值undefined进行比较。 您需要将它与字符串"undefined"进行比较。

我还会移动该检查，以便具有类似标志名称（ isClient 、 isCidGlobal ）的变量实际上是标志，而不是字符串。 此外，如果window未定义，您的第二行将失败，因为您尝试使用undefined['cid_global'] 。

例如：

const isClient = typeof window !== "undefined";
// *** −−−−−−−−−−−−−−−−−−−−−−−−−−−−^−−−−−−−−−^
const isCidGlobal = isClient && typeof window['cid_global'] !== "undefined";
// *** −−−−−−−−−−−−−^^^^^^^^^^^^−−−−−−−−−−−−−−−−−−−−−−−−−−−^^^^^^^^^^^^^^^^

const _window = isClient ? window : {}; // ** Removed the comparison

// *** Replaced everything before the ? with just `isCidGlobal`
const cid_global = isCidGlobal ? _window['cid_global'] : {brand: 'unknown', locale: {country: '', language: ''}, ENV: '', accessPath: '', contrastPreference: '' };

但除非您将它用于其他用途，否则您不需要_window ：

const isClient = typeof window !== "undefined";
const isCidGlobal = isClient && typeof window['cid_global'] !== "undefined";
const cid_global = isCidGlobal ? window['cid_global'] : {brand: 'unknown', locale: {country: '', language: ''}, ENV: '', accessPath: '', contrastPreference: '' };

或者，除非您将它用于其他用途，否则isCidGlobal ：

const isClient = typeof window !== "undefined";
const isCidGlobal = (isClient && window['cid_global']) || {brand: 'unknown', locale: {country: '', language: ''}, ENV: '', accessPath: '', contrastPreference: '' };

（当然，该版本假设window['cid_global']不是其他一些虚假值，但它看起来像是一个安全的假设。）