Javascript如何遍历对象以拾取选定的项目

Question

我想遍历 data 对象并从中选择两个项目，即 year 和 revenue 并将其放入一个新对象中

var data [{"year": 2014, "revenue": 20000, "costs": 10000, "hours": 50}, {"year": 2015, "revenue": 30000, "costs": 20000, "hours": 54}, {"year": 2016, "revenue": 30000, "costs": 10000, "hours": 40}]

var pickedData = {};

data.forEach(output)

function output(d) {
     Object.assign({}, pickedData.Year = d.year),
     Object.assign({}, pickedData.Revenue = d.revenue)
}

该代码有效，但仅将 data 中的最后一项分配给新对象 pickedData，这意味着它会循环它但不会每次都为对象分配值通过。我怎样才能得到这样的输出:

console.log(pickedData)
 [{Year: 2014, Revenue: 20000}, {Year: 2015, Revenue: 30000}, {Year: 2016, Revenue: 30000}]

Answer 1

您可以改用 map() 方法并返回新数组作为结果。

var data = [{"year": 2014, "revenue": 20000, "costs": 10000, "hours": 50}, {"year": 2015, "revenue": 30000, "costs": 20000, "hours": 54}, {"year": 2016, "revenue": 30000, "costs": 10000, "hours": 40}]

var result = data.map(({year, revenue}) => ({year, revenue}));
console.log(result)