使用計算屬性鍵訪問對象值

Question

我正在寫一個應該得到數組的最小項的小幫手。

該函數將Array作爲第一參數，並使用訪問對象屬性「休息」參數的「路徑」。

例：minItem(stops, 'duration', 'total');

的console.log：// [object object][duration][total]

預期：// 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');

Answer 1

由最小值陣列上使用Math#min獲取最小值，使用0123創建。爲了獲得在args路徑值，你可以用Array#reduce迭代鍵：

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'));