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maloneleo88
V2EX  ›  JavaScript

高德 web API 的 callba 应该怎么用?

  •  
  •   maloneleo88 · 2022-05-08 19:35:17 +08:00 · 1569 次点击
    这是一个创建于 930 天前的主题,其中的信息可能已经有所发展或是发生改变。

    API 接口 https://lbs.amap.com/api/webservice/guide/api/georegeo

    返回数据

    {"status":"1","info":"OK","infocode":"10000","count":"1","geocodes":[{"formatted_address":"北京市朝阳区阜通东大街 6 号","country":"中国","province":"北京市","citycode":"010","city":"北京市","district":"朝阳区","township":[],"neighborhood":{"name":[],"type":[]},"building":{"name":[],"type":[]},"adcode":"110105","street":"阜通东大街","number":"6 号","location":"116.482086,39.990496","level":"门牌号"}]}
    

    比如我的 callback=getGPS

    $.get('url', getGPS) ???

    刚学到回调函数这,回调函数就是写好一个函数,当作参数传给另一个函数调用,那这个 callback 在这个 api 中有什么意义?应该怎么使用?

    我现在直接

                       var results = $.get(url, getGeocodes);
    
                        function getGeocodes() {
                            var tude = results.responseJSON.geocodes[0].location;
                            $("#id_detect_coordinate").val(tude);
                        }
                    }
    

    我没有填那个 callback,直接拿到返回数据, 所以那个 callback 到底有什么用?正确使用方法是什么?

    maloneleo88
        1
    maloneleo88  
    OP
       2022-05-08 23:18:56 +08:00
    明白了。

    ```
    //回调函数 getGPS
    <script>
    function getGPS(data) {
    //do someting
    }
    </script>

    <script src="请求地址巴拉巴拉&callback=回调函数">
    </script>
    ```
    没加 callback 服务器返回的是
    ```
    {"status":"1","info":"OK","infocode":"10000","count":"1","geocodes":[{"formatted_address":"北京市朝阳区阜通东大街 6 号","country":"中国","province":"北京市","citycode":"010","city":"北京市","district":"朝阳区","township":[],"neighborhood":{"name":[],"type":[]},"building":{"name":[],"type":[]},"adcode":"110105","street":"阜通东大街","number":"6 号","location":"116.482086,39.990496","level":"门牌号"}]}
    ```
    加了 callback 以后,服务器返回的是
    ```
    getGPS({"status":"1","info":"OK","infocode":"10000","count":"1","geocodes":[{"formatted_address":"北京市朝阳区阜通东大街 6 号","country":"中国","province":"北京市","citycode":"010","city":"北京市","district":"朝阳区","township":[],"neighborhood":{"name":[],"type":[]},"building":{"name":[],"type":[]},"adcode":"110105","street":"阜通东大街","number":"6 号","location":"116.482086,39.990496","level":"门牌号"}]})
    ```

    也就是说,服务器直接把 回调函数名+(返回数据) 给返回来了。 所以导致 getGPS(data)接收到的实参对象,所以执行 getGPS(data),此时 data 从形参变实参了,在再回调函数中 do something



    问题是,用$.get 直接拿数据不香吗? API 这个回调函数的方式除了解决跨域 还有啥用处?
    typedefine
        2
    typedefine  
       2022-05-09 10:25:47 +08:00
    JSONP 这么老的方案 居然还有不知道的
    maloneleo88
        3
    maloneleo88  
    OP
       2022-05-09 11:55:38 +08:00
    @typedefine 刚学 汗!
    cutemurphy2000
        4
    cutemurphy2000  
       2022-05-12 10:52:31 +08:00
    @maloneleo88 哈哈 抱一下·
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