javascript - 解析这个 Json 响应并在 JavaScript 中循环遍历数组

Question

有很多关于这个的帖子，但我无法弄清楚这个。这是来自 Ajax 函数的 json 响应：

var obj = {
    "3901": 10,
    "3900": 3,
    "3902": 9,
    "3899": 2,
    "3274": 4,
    "3257": 9.5,
    "3883": 12,
    "3881": "12",
    "3876": 3,
    "3267": 14,
    "3258": 2.5,
    "3260": 13.5,
    "3259": 6.5,
    "3264": 4.5,
    "3268": 2,
    "3273": 5.5,
    "3266": 17,
    "3270": 9,
    "3271": 8,
    "3275": 2,
    "3263": 2.5,
    "3261": 2.5,
    "3265": "37",
    "3281": 3,
    "3277": 7.5,
    "3278": 0.5,
    "3276": 7,
    "3898": 8,
    "3891": 7,
    "3293": 1,
    "3895": 1,
    "3256": 2,
    "3903": 10,
    "3840": 2,
    "3886": 11,
    "3884": 8,
    "3872": 2,
    "3874": 4,
    "3284": 1.5,
    "3302": 1.25,
    "3304": 5,
    "3306": 2,
    "3329": 1.5,
    "3330": 2,
    "3333": 6,
    "3335": 7.5,
    "3327": 1,
    "3934": 8,
    "3935": 9,
    "3939": 1,
    "3933": 3,
    "3937": 1,
    "3322": 3.5,
    "3890": 1,
    "3878": 5,
    "3880": 4,
    "3879": 1,
    "3889": 2,
    "3852": 2,
    "3877": 2
}

我有一个 ID：3902、3883、4567 和 3878

我只需要遍历这 4 个 id 并检查它们是否在 json 响应中，以及它们是否获得了与之关联的值，如果没有返回 0。例如：

3902 将返回 9，4567 将返回 0

谢谢。

标签： javascriptarraysjson

Answer 1

您可以将所有 id 放入一个名为 的数组ids中，然后.map()在该数组上使用。对于id数组中的每个，您可以使用obj[id]. 如果它不存在，它将返回undefined。如果发生这种情况，您可以通过以下方式使用默认0值||：

请参见下面的示例：

const obj = {"3901":10,"3900":3,"3902":9,"3899":2,"3274":4,"3257":9.5,"3883":12,"3881":"12","3876":3,"3267":14,"3258":2.5,"3260":13.5,"3259":6.5,"3264":4.5,"3268":2,"3273":5.5,"3266":17,"3270":9,"3271":8,"3275":2,"3263":2.5,"3261":2.5,"3265":"37","3281":3,"3277":7.5,"3278":0.5,"3276":7,"3898":8,"3891":7,"3293":1,"3895":1,"3256":2,"3903":10,"3840":2,"3886":11,"3884":8,"3872":2,"3874":4,"3284":1.5,"3302":1.25,"3304":5,"3306":2,"3329":1.5,"3330":2,"3333":6,"3335":7.5,"3327":1,"3934":8,"3935":9,"3939":1,"3933":3,"3937":1,"3322":3.5,"3890":1,"3878":5,"3880":4,"3879":1,"3889":2,"3852":2,"3877":2};

const ids = [3902, 3883, 4567, 3878];
const res = ids.map(id => obj[id] || 0);
console.log(res);