使用计算属性键访问对象值
问题描述:
我正在写一个应该得到数组的最小项的小帮手。使用计算属性键访问对象值
该函数将Array
作为第一参数,并使用访问对象属性“休息”参数的“路径”。
例:minItem(stops, 'duration', 'total');
的console.log:// [object object][duration][total]
预期:// Number, Which is the value of total
const stops =
[{"transport":"train","departure":"Paris","arrival":"Madrid","duration":
{"h":"03","m":"15","total":195},"cost":160,"discount":0,
"reference":"TPM0315","initialPrice":160},
{"transport":"bus","departure":"Paris","arrival":"Madrid",
"duration":{"h":"06","m":"45","total":405},"cost":30,"discount":25,
"reference":"BPM0645","initialPrice":40},
{"transport":"car","departure":"Paris","arrival":"Madrid","duration":
{"h":"05","m":"45","total":345},"cost":120,"discount":0,
"reference":"CPM0545","initialPrice":120}];
/** @function minItem */
const minItem = (array, ...args) => {
const keys = `['${[...args].join('\'][\'')}']`;
array.reduce((a, b) => {
console.log(b + keys);
return a + keys <= b + keys ? a : b;
}, {});
};
minItem(stops, 'duration', 'total');
答
由最小值阵列上使用Math#min获取最小值,使用0123创建。为了获得在args
路径值,你可以用Array#reduce迭代键:
const stops = [{"transport":"train","departure":"Paris","arrival":"Madrid","duration":{"h":"03","m":"15","total":195},"cost":160,"discount":0,"reference":"TPM0315","initialPrice":160},{"transport":"bus","departure":"Paris","arrival":"Madrid","duration":{"h":"06","m":"45","total":405},"cost":30,"discount":25,"reference":"BPM0645","initialPrice":40},{"transport":"car","departure":"Paris","arrival":"Madrid","duration":{"h":"05","m":"45","total":345},"cost":120,"discount":0,"reference":"CPM0545","initialPrice":120}];
/** @function minItem */
const getPathValue = (src, path) => path.reduce((p, k) => typeof p === 'object' ? p[k] : p, src);
const minItem = (array, ...args) => Math.min(...array.map((o) => getPathValue(o, args)));
console.log(minItem(stops, 'duration', 'total'));