javascript - 如何使用 Javascript 将数组的值转换为每个条目中的不同键？

Question

我有以下数据集。数组中的每个条目都有一个名为“Type”的键，共有三种类型。

var data = [
        {date: "12/27/2012", Type: "http_200", Val: 190, Irrelevant: "Stringa"},
        {date: "12/28/2012", Type: "http_200", Val: 10, Irrelevant: "Stringb"},
        {date: "12/29/2012", Type: "http_404", Val: 100, Irrelevant: "Stringc"},
        {date: "12/30/2012", Type: "http_302", Val: 90, Irrelevant: "Stringd"},
        ];

我希望每种类型都成为自己的键，其值与“Val”的值相同

Result = [
        {date: "12/27/2012",Type: "http_200", Val: 190, http_404: 0, http_200: 190, http_302: 0},
        {date: "12/28/2012",Type: "http_200", Val: 10, http_404: 0, http_200: 10, http_302: 0},
        {date: "12/29/2012",Type: "http_404",Val: 100, http_404: 100, http_200: 0, http_302: 0},
        {date: "12/30/2012",Type: "http_302",Val: 90, http_404: 0, http_200: 0, http_302: 90},
        ];

最有效的方法是什么？我将在一个非常大的数据集上执行此操作。

此外，是否可以在不知道所有类型的情况下执行此操作，以便我可以轻松地在任何给定的键上运行它。

我可以尝试如下操作，但问题是考虑到数据量和类型，对每个键和值执行此操作非常乏味

data.forEach(function (d) {
    if(d.Type = 'http_200'){d.http_200=d.Val, d.http_404=0, http_302=0} else {d.http_200=d.0, d.http_404=0, http_302=0};
    if(d.Type = 'http_404'){d.http_200=0, d.http_404=d.Val, http_302=0} else {d.http_200=d.0, d.http_404=0, http_302=0};
    if(d.Type = 'http_302'){d.http_200=0, d.http_404=0, http_302=d.Val} else {d.http_200=d.0, d.http_404=0, http_302=0};
    });

Answer 1

您需要循环遍历数组两次。首先提取所有类型，然后创建值。

var data = [
    {date: "12/27/2012", Type: "http_200", Val: 190, Irrelevant: "Stringa"},
    {date: "12/28/2012", Type: "http_200", Val: 10, Irrelevant: "Stringb"},
    {date: "12/29/2012", Type: "http_404", Val: 100, Irrelevant: "Stringc"},
    {date: "12/30/2012", Type: "http_302", Val: 90, Irrelevant: "Stringd"},
];
var types = [];

function getTypes(data){
    for (var i = 0, endi = data.length; i<endi; ++i){
        var obj = data[i]
        if(types.indexOf(obj.Type)) types.push(obj.Type);
    }
}

function addAllTypesToData(data, types){
    for (var data_i = 0, data_endi = data.length; data_i<data_endi; ++data_i){
        var obj = data[data_i];
        for (var type_i = 0, type_endi = types.length; type_i<type_endi; ++type_i){
            obj[types[type_i]] = (obj.Type === types[type_i]) ? obj.Val : 0;
        }
    }
}

getTypes(data);
addAllTypesToData(data, types);