For循環將所有對象值設置爲最後一個實例

Question

我試圖遍歷for循環來對數組進行5次排序。

let sortedCities = {}; 
for (let i = 0; i < 5; i++) { 
    sortedCities[i] = darkSkyHelper.sortCities(info,unsortedCities,i); 
    console.log(sortedCities[i]); 
} 
console.log(sortedCities); 

static sortCities(info, cities, day) { 
    let sortedCities = cities.sort(function(a,b) { 
     return info[b].daily.data[day].precipProbability - info[a].daily.data[day].precipProbability; 
    }) 
    return sortedCities; 
    } 

第一的console.log顯示每個循環中的期望的輸出，而第二顯示器與每個對象值等於從環路

["cin", "cle", "col", "nya", "laa", "was", "tex"] 
["was", "nya", "cle", "cin", "col", "laa", "tex"] 
["cle", "cin", "was", "nya", "laa", "col", "tex"] 
["laa", "col", "cle", "cin", "was", "nya", "tex"] 
["col", "tex", "cle", "laa", "cin", "was", "nya"] 

Object {..} 
0: Array[7] 
0: "col" 
1: "tex" 
2: "cle" 
3: "laa" 
4: "cin" 
5: "was" 
6: "nya" 
length: 7 
__proto__: Array[0] 
1: Array[7] 
0: "col" 
1: "tex" 
2: "cle" 
3: "laa" 
4: "cin" 
5: "was" 
6: "nya" 
... 

Answer 1

每次調用時的最後一個運行的輸出的對象sortCities你正在返回對同一個數組的引用，只是按不同的順序排序。你需要每次創建一個新的數組。有幾種方法可以做到這一點，包括slice：

static sortCities(info, cities, day) { 
    let sortedCities = cities.sort(function(a,b) { 
     return info[b].daily.data[day].precipProbability - info[a].daily.data[day].precipProbability; 
    }) 
    return sortedCities.slice(0); 
}