javascript - 尝试拉取数据时与 API 的差异

Question

我在使用 Jquery 为学校项目从 API 中提取一些数据时遇到困难。

如果我使用以下 coinmakeetcap API，我会得到以下响应

https://api.coinmarketcap.com/v1/ticker/bitcoin/

[
{
    "id": "bitcoin", 
    "name": "Bitcoin", 
    "symbol": "BTC", 
    "rank": "1", 
    "price_usd": "8854.92", 
    "price_btc": "1.0", 
    "24h_volume_usd": "6759730000.0", 
    "market_cap_usd": "150480289107", 
    "available_supply": "16993975.0", 
    "total_supply": "16993975.0", 
    "max_supply": "21000000.0", 
    "percent_change_1h": "-0.13", 
    "percent_change_24h": "0.12", 
    "percent_change_7d": "8.3", 
    "last_updated": "1524459272"
}
]

我能够使用这段代码获取比特币符号并将其放入一个变量中

> $.getJSON('https://api.coinmarketcap.com/v1/ticker/btc/',
> function(data){                   
>               var symbol   = (data[0].symbol)
>      })

一旦我有了它，我就可以将它放在一个 div 中。

但是，当我使用 cryptocompare API 时，我没有得到任何返回

https://min-api.cryptocompare.com/data/coin/generalinfo?fsyms=BTC,&tsym=USD

 $.getJSON('https://min-api.cryptocompare.com/data/coin/generalinfo?fsyms=BTC&tsym=USD', function(data){
                    var symbol     = (data[0].Internal)
                           });

这是回应-

{
"Message": "Success",
"Type": 100,
"Data": [
    {
        "CoinInfo": {
            "Id": "1182",
            "Name": "BTC",
            "FullName": "Bitcoin",
            "Internal": "BTC",
            "ImageUrl": "/media/19633/btc.png",
            "Url": "/coins/btc/overview",
            "Algorithm": "SHA256",
            "ProofType": "PoW",
            "NetHashesPerSecond": 27483320229.3688,
            "BlockNumber": 518932,
            "BlockTime": 600,
            "BlockReward": 12.5,
            "Type": 1,
            "DocumentType": "Webpagecoinp"
        },
        "ConversionInfo": {
            "Conversion": "direct",
            "ConversionSymbol": "",
            "CurrencyFrom": "BTC",
            "CurrencyTo": "USD",
            "Market": "CCCAGG",
            "Supply": 16986575,
            "TotalVolume24H": 380849.0498955779,
            "SubBase": "5~",
            "SubsNeeded": [
                "5~CCCAGG~BTC~USD"
            ],
            "RAW": [
                "5~CCCAGG~BTC~USD~4~8875.23~1524460635~0.00477012~42.152119404000004~231254719~10820.885574747872~96327075.76938197~66326.58563159907~593473019.8524572~8823.46~8917.05~8804.2~8864.31~9065~8780.91~Bitfinex~7ffe9"
            ]
        }
    }
]

为什么第二段代码不起作用？请帮忙!

Answer 1

第二个 API 返回一个对象(JSON 格式)，而不是数组 - 看看第一个字符是 { 以及它如何具有键和值？您需要访问适当的属性以获得所需的值。 [0] 符号表示您正在尝试访问数组的第一个元素，但在这种情况下外部对象不是数组。

$.getJSON('https://min-api.cryptocompare.com/data/coin/generalinfo?fsyms=BTC&tsym=USD',
  function(data){
    var symbol = data.Data[0].CoinInfo.Internal;
  });