如何缩短这个三元运算符？

Question

我有存储从数据库检索到的信息的代码。

因为我的 JavaScript 代码是异步的并且需要时间来检索数据，我认为它会存储错误而不是数据。

有一个现有的辅助函数可以检查嵌套对象的最高级别。我想让这个函数更短，并阻止三元运算符返回''。

const ratingAggregateCount = IsNestedObjectKeyPresent(currentProjectDetails, "ratingAggregate", "count") ? currentProjectDetails.ratingAggregate.count : '';

const ratingAggregateAverage = sNestedObjectKeyPresent(currentProjectDetails, "ratingAggregate", "average") ? currentProjectDetails.ratingAggregate.average.toFixed(1) : '';

const ratingWiseCounts = (!!currentProjectDetails.ratingWiseCounts ) ? currentProjectDetails.ratingWiseCounts : '';

Answer 1

如果IsNestedObjectKeyPresent 助手主要用于此目的，则可以使用返回空字符串的助手：

const ratingAggregateCount = nestedObjectKeyOrEmptyString(currentProjectDetails, "ratingAggregate", "count");

这是Lodash get 等安全导航函数中的默认值参数的用途。

没有必要使用与条件相同的三进制值，它可能会短路：

const ratingWiseCounts = currentProjectDetails.ratingWiseCounts || '';

如果已知值是假的唯一可能性是undefined，则可以使用解构默认值：

const { ratingWiseCounts = '' } = currentProjectDetails;

Answer 2

您可以使用短路运算符&&

const ratingAggregateCount = IsNestedObjectKeyPresent(currentProjectDetails, "ratingAggregate", "count") && currentProjectDetails.ratingAggregate.count;

const ratingAggregateAverage = sNestedObjectKeyPresent(currentProjectDetails, "ratingAggregate", "average") && currentProjectDetails.ratingAggregate.average.toFixed(1);

const ratingWiseCounts = (!!currentProjectDetails.ratingWiseCounts ) && currentProjectDetails.ratingWiseCounts;

例子

const a = true && "assign";
const b = "something" && "assign";
const c = false && "not assign";
const d = undefined && "not assign";
const e = null && "not assign";
const f = "" && "not assign";

console.log({a,b,c,d,e,f});