[英]return array of objects from another grouped by many object properties
[英]Write a pure function to return one object from inner properties another objects?
做一些数据转换练习并陷入困境。 我有一个对象,我想要转换为from (starting)
- > to (expected ending)
下面描述的to (expected ending)
输出。 我正在尝试使用Array.reduce
和Object.assign
来保持输出纯净。 但我无法让它正常工作。
/**
* from (starting): {topic: {id: 2}, products: {id: 3}}
* to (expected ending): {topic: 2, products: 3}
*/
const starting = {topic: {id: 2}, products: {id: 3}};
const ending = Object.keys(starting).reduce((p, key) => {
if(!p[key]) p[key] = key;
return Object.assign(p[key], starting[key].id);
}, {})
您可以使用reduce
,只需记住在每次迭代后返回起始对象。
function convert(start) { return Object.keys(starting).reduce((o, key) => { o[key] = start[key].id; return o; }, {}); } const starting = {topic: {id: 2}, products: {id: 3}}; console.log(convert(starting));
尝试这个:
var starting = {topic: {id: 2}, products: {id: 3}};
var ending = Object.keys(starting).reduce((p, key) => {
p[key] = starting[key].id;
return p;
}, {})
这将创建一个新对象,因此不需要Object.assign
等来保持输出纯净。
我认为reduce()
不是正确的工具。
尝试使用forEach()
迭代starting
的键:
const starting = {topic: {id: 2}, products: {id: 3}}; const ending = {}; Object.keys(starting).forEach(p => ending[p] = starting[p].id); console.log(ending);
纯函数解决方案需要您在每次迭代时返回一个新对象:
function convert(start) { return Object.keys(starting).reduce((o, key) => Object.assign({}, { [key]: start[key].id }, o), {}); } const starting = {topic: {id: 2}, products: {id: 3}}; console.log(convert(starting));
使用对象传播使它更清洁:
function convert(start) { return Object.keys(starting).reduce((o, key) => ({ ...o, [key]: start[key].id }), {}); } const starting = {topic: {id: 2}, products: {id: 3}}; console.log(convert(starting));
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