javascript - 如何使用 JavaScript 抓取 JSON 页面并收集数据

Question

我想抓取 https://api.coindesk.com/v1/bpi/currentprice/BTC.json/ 并收集比特币的价格，并将其保存到一个变量中。到目前为止，这是我的 js/jQuery 代码

$.getJSON('http://www.whateverorigin.org/get?url=' + encodeURIComponent('https://api.coindesk.com/v1/bpi/currentprice/BTC.json/') + '&callback=?', function(data){
    console.log(data.contents);
    var za = $((data.contents).find("rate_float").text();
    alert(za)
}));

我不断收到错误:

Uncaught SyntaxError: missing ) after argument list and it points to line:

var za = $((data.contents).find("rate_float").text();

不知道怎么回事。我一遍又一遍地检查它，但所有括号都已关闭。任何帮助表示赞赏。谢谢

Answer 1

返回值是一个 JSON 字符串。您需要解析以便将该字符串转换为 js 对象，例如:

{
     "time": {
         "updated": "Mar 28, 2018 16:58:00 UTC",
         "updatedISO": "2018-03-28T16:58:00+00:00",
         "updateduk": "Mar 28, 2018 at 17:58 BST"
     },
     "disclaimer": "This data was produced from the CoinDesk Bitcoin Price Index (USD). Non-USD currency data converted using hourly conversion rate from openexchangerates.org",
     "bpi": {
         "USD": {
             "code": "USD",
             "rate": "7,882.7938",
             "description": "United States Dollar",
             "rate_float": 7882.7938
         },
         "BTC": {
             "code": "BTC",
             "rate": "1.0000",
             "description": "Bitcoin",
             "rate_float": 1
         }
     }
 }

为了获得 USD rate_float 你可以这样写:

var za = JSON.parse(data.contents).bpi.USD.rate_float;

完整代码:

$.getJSON('http://www.whateverorigin.org/get?url=' +
        encodeURIComponent('https://api.coindesk.com/v1/bpi/currentprice/BTC.json') + '&callback=?', function (data) {
    console.log(data.contents);
    var za = JSON.parse(data.contents).bpi.USD.rate_float;
    alert(za)
});