如何在javascript中使用對象數組映射屬性

Question

我只是想使用map完全返回數組，然后再開始下一個函數。 但是我在安慰它時收到不完整的數組

這是我的示例數組：

data = [{
        "a": 1,
        "b": 5,
        "c": 9,
        "d": 1,
        "e": 4,
        "f": 44,
        "g": 23,
        "h": 12,
        "i": 22,
        "j": 23,
        "k": [{
            "a": 1,
            "b": 5,
            "c": 9,
            "d": 1
        }, {
            "a": 1,
            "b": 5,
            "c": 9,
            "d": 1
        }]
    },
    {
        "a": 2,
        "b": 6,
        "c": 10,
        "d": 1,
        "e": 4,
        "f": 44,
        "g": 23,
        "h": 12,
        "i": 22,
        "j": 23,
        "k": [{
            "a": 1,
            "b": 5,
            "c": 9,
            "d": 1
        }, {
            "a": 1,
            "b": 5,
            "c": 9,
            "d": 1
        }]
    },
    {
        "a": 3,
        "b": 7,
        "c": 11,
        "d": 1,
        "e": 4,
        "f": 44,
        "g": 23,
        "h": 12,
        "i": 22,
        "j": 23,
        "k": [{
            "a": 1,
            "b": 5,
            "c": 9,
            "d": 1
        }, {
            "a": 1,
            "b": 5,
            "c": 9,
            "d": 1
        }]
    },
    {
        "a": 4,
        "b": 8,
        "c": 12,
        "d": 1,
        "e": 4,
        "f": 44,
        "g": 23,
        "h": 12,
        "i": 22,
        "j": 23,
        "k": [{
            "a": 1,
            "b": 5,
            "c": 9,
            "d": 1
        }, {
            "a": 1,
            "b": 5,
            "c": 9,
            "d": 1
        }]
    }
]

var result = data.map(x=>({...x}));     
console.log(result);

這是我的數組時，我安慰它：

[{
        "a": 1,
        "b": 5,
        "c": 9,
        "d": 1,
        "e": 4,
        "f": 44,
        "g": 23,
        "h": 12,
        "i": 22,
        "j": 23,
        "k": []
    },
    {
        "a": 2,
        "b": 6,
        "c": 10,
        "d": 1,
        "e": 4,
        "f": 44,
        "g": 23,
        "h": 12,
        "i": 22,
        "j": 23,
        "k": []
    },
    {
        "a": 3,
        "b": 7,
        "c": 11,
        "d": 1,
        "e": 4,
        "f": 44,
        "g": 23,
        "h": 12,
        "i": 22,
        "j": 23,
        "k": []
    },
    {
        "a": 4,
        "b": 8,
        "c": 12,
        "d": 1,
        "e": 4,
        "f": 44,
        "g": 23,
        "h": 12,
        "i": 22,
        "j": 23,
        "k": []
    }
]

當我使用.map()函數時，我希望數組完整。

Answer 1

傳播只是一個淺表副本-因此不會復制內部數組。

對於簡單的深層副本，請使用JSON.stringify和JSON.parse 。

 const data = [{"a":1,"b":5,"c":9,"d":1,"e":4,"f":44,"g":23,"h":12,"i":22,"j":23,"k":[{"a":1,"b":5,"c":9,"d":1},{"a":1,"b":5,"c":9,"d":1}]},{"a":2,"b":6,"c":10,"d":1,"e":4,"f":44,"g":23,"h":12,"i":22,"j":23,"k":[{"a":1,"b":5,"c":9,"d":1},{"a":1,"b":5,"c":9,"d":1}]},{"a":3,"b":7,"c":11,"d":1,"e":4,"f":44,"g":23,"h":12,"i":22,"j":23,"k":[{"a":1,"b":5,"c":9,"d":1},{"a":1,"b":5,"c":9,"d":1}]},{"a":4,"b":8,"c":12,"d":1,"e":4,"f":44,"g":23,"h":12,"i":22,"j":23,"k":[{"a":1,"b":5,"c":9,"d":1},{"a":1,"b":5,"c":9,"d":1}]}]; const res = data.map(x => JSON.parse(JSON.stringify(x))); console.log(res); 

 .as-console-wrapper { max-height: 100% !important; top: auto; } 

還有一個不太支持的Object.fromEntries此功能目前處於草擬階段：

 const data = [{"a":1,"b":5,"c":9,"d":1,"e":4,"f":44,"g":23,"h":12,"i":22,"j":23,"k":[{"a":1,"b":5,"c":9,"d":1},{"a":1,"b":5,"c":9,"d":1}]},{"a":2,"b":6,"c":10,"d":1,"e":4,"f":44,"g":23,"h":12,"i":22,"j":23,"k":[{"a":1,"b":5,"c":9,"d":1},{"a":1,"b":5,"c":9,"d":1}]},{"a":3,"b":7,"c":11,"d":1,"e":4,"f":44,"g":23,"h":12,"i":22,"j":23,"k":[{"a":1,"b":5,"c":9,"d":1},{"a":1,"b":5,"c":9,"d":1}]},{"a":4,"b":8,"c":12,"d":1,"e":4,"f":44,"g":23,"h":12,"i":22,"j":23,"k":[{"a":1,"b":5,"c":9,"d":1},{"a":1,"b":5,"c":9,"d":1}]}]; const res = data.map(x => Object.fromEntries(Object.entries(x))); console.log(res); 

 .as-console-wrapper { max-height: 100% !important; top: auto; } 

Answer 2

這不是因為地圖功能，而是因為控制台。 如果控制台太長，則可以剪切輸出。 如果您需要查看完整結果，可以進行

console.log(JSON.stringify(result));

或其他一些代碼修改嵌套數組（ data[0].k = [] ）。 由於要進行高級復制，因此您將看到空數組。 在這種情況下，您應該復制原始data 。 對於這種情況，您有一個非常有用的lib lodash

因此，您可以執行以下操作：

var result = _.cloneDeep(data);