javascript - 复制数组元素修改并再次添加

Question

原始数组是newData。我想向 newData 添加一个数组元素，并且添加的数组元素应具有 Rank 1。

问题是两条记录的排名都更新为 1。第二条记录的排名应为 1，第一条记录的排名应为 null

请告诉我我在这里做错了什么。

let newData = [{
    "key1": {
        "cc":'IND'   
    },          
    "key2": {
        "rank": null
    }
}];

let setData = newData.concat(newData.slice());

setData.forEach(data => { 
    data.key2.rank =+ 1;
});

Answer 1

您可以尝试以下操作

let newData = [{"key1": {"cc":'IND' }, "key2": {"rank": null}}];

    // Concatenate arrays use spread operator and can use map rather than slice
    let setData = [...newData, ...newData.map(data => { 
        /* Objects are passed by reference, you need to break the reference
         * to create the clone of the object. */
        data = JSON.parse(JSON.stringify(data));
        data.key2.rank =+ 1; 
        return data;
    })];

console.log(setData);