Vue获取json数组数据的疑问

刚学vue，下面这个json，我想获取exchangeTrades下的buyRate值，谢谢。

{
    "code": 0,
    "data": [
        {
            "allTrades": {
                "buyQty": 0,
                "buyRate": 0.5189,
                "cTime": 1584957514000,
                "exchange": "all",
                "futureType": "all",
                "id": 0,
                "price": 0,
                "sellQty": 0,
                "sellRate": 0.4811,
                "symbol": "BTC",
                "timestamp": 1584957514000,
                "type": "1h"
            },
            "exchangeTrades": [
                {
                    "buyQty": 972958,
                    "buyRate": 0.5063,
                    "cTime": 1584957514006,
                    "exchange": "Huobi",
                    "futureType": "quarter",
                    "id": 0,
                    "price": 0,
                    "sellQty": 948668,
                    "sellRate": 0.4937,
                    "symbol": "BTC",
                    "timestamp": 1584957514006,
                    "type": "1h"
                },
                {
                    "buyQty": 292280,
                    "buyRate": 0.509,
                    "cTime": 1584957514016,
                    "exchange": "Okex",
                    "futureType": "swap",
                    "id": 0,
                    "price": 0,
                    "sellQty": 281993,
                    "sellRate": 0.491,
                    "symbol": "BTC",
                    "timestamp": 1584957514016,
                    "type": "1h"
                },
                {
                    "buyQty": 16451622,
                    "buyRate": 0.5318,
                    "cTime": 1584957514010,
                    "exchange": "Bitmex",
                    "futureType": "swap",
                    "id": 0,
                    "price": 0,
                    "sellQty": 14486032,
                    "sellRate": 0.4682,
                    "symbol": "XBT",
                    "timestamp": 1584957514010,
                    "type": "1h"
                },
                {
                    "buyQty": 1862092,
                    "buyRate": 0.5219,
                    "cTime": 1584957514003,
                    "exchange": "Okex",
                    "futureType": "quarter",
                    "id": 0,
                    "price": 0,
                    "sellQty": 1706101,
                    "sellRate": 0.4781,
                    "symbol": "BTC",
                    "timestamp": 1584957514003,
                    "type": "1h"
                }
            ]
        }
    ],
    "dialog": {
        "cancelAndClose": false,
        "cancelBtn": "",
        "cancelColor": "",
        "code": "0",
        "confirmBtn": "",
        "confirmColor": "",
        "content": "",
        "contentColor": "",
        "time": "",
        "title": "OK",
        "titleColor": "",
        "type": "3",
        "url": ""
    }
}

参考GPT和自己的思路：

可以通过以下代码来获取exchangeTrades下的buyRate值：

//假设data为上述JSON数据
let buyRateArr = data.data[0].exchangeTrades.map(item => item.buyRate);
console.log(buyRateArr);  //输出[0.5063, 0.509, 0.5318, 0.5219]

详解：

1. 通过data.data[0]获取到最外层的对象。
2. 对象中的exchangeTrades是一个数组，可以使用map()方法，遍历数组中每个对象。
3. 在map()方法的回调函数中，使用箭头函数简写，并通过item.buyRate获取每个对象中的buyRate值。
4. 最终返回一个新的数组，包含所有的buyRate值。