处理Json对象时遇到的乱序问题

January 28, 2022

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##数据场景
在处理类似这样的Json对象时：
```json
{
  "AED": "United Arab Emirates Dirham",
  "AFN": "Afghan Afghani",
  "ALL": "Albanian Lek",
  "AMD": "Armenian Dram",
  "ANG": "Netherlands Antillean Guilder",
  "AOA": "Angolan Kwanza",
  "ARS": "Argentine Peso",
  "AUD": "Australian Dollar",
  "BSD": "Bahamian Dollar",
  "BTC": "Bitcoin",
  "BTN": "Bhutanese Ngultrum",
  "CNH": "Chinese Yuan (Offshore)",
  "CNY": "Chinese Yuan",
  "COP": "Colombian Peso",
  "CRC": "Costa Rican Colón",
  "CUC": "Cuban Convertible Peso",
  "CUP": "Cuban Peso",
  "CVE": "Cape Verdean Escudo",
  "CZK": "Czech Republic Koruna",
  "DJF": "Djiboutian Franc",
  "DKK": "Danish Krone",
  "JEP": "Jersey Pound",
  "JMD": "Jamaican Dollar",
  "JOD": "Jordanian Dinar",
  "JPY": "Japanese Yen",
  "KES": "Kenyan Shilling",
  "KGS": "Kyrgystani Som",
  "KHR": "Cambodian Riel",
  "KMF": "Comorian Franc",
  "KPW": "North Korean Won",
  "MWK": "Malawian Kwacha",
  "MXN": "Mexican Peso",
  "MYR": "Malaysian Ringgit",
  "MZN": "Mozambican Metical",
  "NAD": "Namibian Dollar",
  "NGN": "Nigerian Naira",
  "NIO": "Nicaraguan Córdoba",
  "NOK": "Norwegian Krone",
  "NPR": "Nepalese Rupee",
  "NZD": "New Zealand Dollar",
  "OMR": "Omani Rial"
}
```
可见key已经是有序的了，然后在JavaScript中使用常规的forin去遍历，结果显示的顺序和给过来的顺序不一致。

##原因
这是因为Json数据是无序的键值对，而数组是有序的，直接forin遍历肯定就是无序的。

##解决方法
先将Json对象转为map对象，使用map对象sort方法进行按key值排序，然后再转为数据或者直接遍历处理，结果才是有序的。
** 这里截取我在傻妞插件中使用的方法来说明 **
```javascript
//data为接收到的Json对象
data={"keys":"values"};
//每次返回均为有序
let stringMap = new Map();
for (const key in data) {
    stringMap.set(key, data[key]);
}
countryList = Array.from(stringMap).sort((a, b) => { return a[0].localeCompare(b[0]) })
countryList.forEach(v => {
    Debug(v)
})

//每次返回均为无序
let index=1;
for (key in data) {
    if (index % 45 == 0) {
        msgString = msgString.join("\n");
        sendText(msgString);
        msgString = [];
    }
    msgString.push(index + ". (" + key + ") - " + data[key]);
    index++;
}
```

处理Json对象时遇到的乱序问题