如何将对象数组的值分配到目标对象对应属性并设默认值为null？

需求说明 #

需要将包含url和country属性的对象数组，映射到键名规则为{country}_url的目标对象中，无对应值的属性统一设为null。

输入数据 #

const urlArrayOfObjects = [ 
    {url: 'https://amazon.co.uk', country: 'uk'},
    {url: 'https://amazon.com', country: 'usa'},
    {url: 'https://amazon.ca', country: 'canada'},
    {url: 'https://amazon.es', country: 'spain'}
];

目标对象模板 #

const urlTablesTemplate = {
    short_url_id: "",
    uk_url: "",
    usa_url: "",
    canada_url: "",
    irland_url: "",
    spain_url: "",
    germany_url: "",
    default_country: "",
    default_url: "",
    customer_id: ""
};

期望输出 #

const urlTables = {
    short_url_id: null,
    uk_url: "https://amazon.co.uk",
    usa_url: "https://amazon.com",
    canada_url: "https://amazon.ca",
    irland_url: null,
    spain_url: "https://amazon.es",
    germany_url: null,
    default_country: null,
    default_url: null,
    customer_id: null
};

实现方案 #

核心思路 #

1. 先将输入数组转换为国家-URL映射表，实现快速查找
2. 遍历目标对象模板的所有键，根据键名规则匹配映射表中的值，无匹配则设为null

完整代码 #

const urlArrayOfObjects = [ 
    {url: 'https://amazon.co.uk', country: 'uk'},
    {url: 'https://amazon.com', country: 'usa'},
    {url: 'https://amazon.ca', country: 'canada'},
    {url: 'https://amazon.es', country: 'spain'}
];

const urlTablesTemplate = {
    short_url_id: "",
    uk_url: "",
    usa_url: "",
    canada_url: "",
    irland_url: "",
    spain_url: "",
    germany_url: "",
    default_country: "",
    default_url: "",
    customer_id: ""
};

// 生成国家与URL的映射表
const countryUrlMap = urlArrayOfObjects.reduce((map, item) => {
    map[item.country] = item.url;
    return map;
}, {});

// 生成最终目标对象
const urlTables = Object.fromEntries(
    Object.entries(urlTablesTemplate).map(([key]) => {
        // 匹配{country}_url格式的键
        const countryMatch = key.match(/^(\w+)_url$/);
        if (countryMatch) {
            const country = countryMatch[1];
            // 有对应值则赋值，否则设为null
            return [key, countryUrlMap[country] ?? null];
        }
        // 非国家URL类的键直接设为null
        return [key, null];
    })
);

console.log(urlTables);

方案优势 #

• 高效：时间复杂度为O(n + m)（n为数组长度，m为目标对象键数量），性能优异
• 易扩展：后续新增国家或目标键时，无需修改核心逻辑
• 可读性强：使用reduce、Object.fromEntries等现代JS API，代码逻辑清晰

内容的提问来源于stack exchange，提问作者SamNewbie