javascript - 在此代码中要执行的三元运算符的真值在哪里？

Question

此编码问题的一些背景。我们的 termTopics 函数需要计算调查中每个主题被提及的次数，然后返回一个数组，其中包含按以下顺序提及的次数:智慧城市、艺术资助，然后是交通。

const termTopics = (interviews) => {
  const count = interviews.reduce((acc, cv) => {
    return {...acc, [cv]: acc[cv] ? acc[cv]+1 : 1}
  }, {})
  return [count['smart city'], count['arts funding'], count['transportation']];
}

我无法理解的是扩展运算符，以及它如何为三元运算符创建一个真实的语句来进行操作。

Answer 1

const count = interviews
  .reduce((resultObject, interview) => {
    // We are creating an object through the reduce function by iterating through the interviews array.
    // At each iteration we will modify the result object according to the current array interview item value
    return {
      // First we copy the object we have so far
      ...resultObject,
      // Then we set the property corresponding to the current item 
      [interview]: resultObject[interview] 
        // If it is not the first time we have seen this item, the object property already exists and we update it by adding one to its value
        ? resultObject[interview] + 1 
         // Otherwise we create a new property and set it to one
        : 1
    }
  }, {})