如何在javascript中获取2d数组的长度，并在js创建的动态div中显示数据

Question

我所需要的

• 我需要在图标上显示数字。
• 我需要使用使用javascript的数组从输入中生成动态div。

阵列结构

            Array
        (
            [0] => Array
            (
                [id] => 50615
                [des] => PHARMA Pro&Pack Expo 2015 is organized by IPMMA and will be held at Mumbai, the economic capital of India. This show helps the exhibitors from all ove
                [membership] => 0
                [name] => Pharma Pro&Pack Expo
                [abbr_name] => Pharma Pro&Pack Expo
                [paid] => 0
                [event_wrapper] => 33587
                [event_samll_wrapper] => http://im.gifbt.com/industry/27-350x210.jpg
                [event_url] => pharma-propack-expo
                [website] => http://www.pharmapropack.com
                [eventType] => 1
                [venue_name] => Bombay Convention & Exhibition Centre (BCEC)
                [startDate] => 2015-05-13
                [endDate] => 2015-05-15
                [city] => Mumbai
                [country] => India
                [country_url] => india
                [country_shortname] => India
                [industry_id] => 27
                [industry_name] => Medical & Pharmaceutical
                [industry_url] => medical-pharma
                [event_status] => 
                [total_visitors] => 144
                [total_exhibitor] => 0
                [total_speakers] => 0
            )

            [1] => Array
            (
                [id] => 57271
                [des] => The Iphex is a well acknowledged event in the pharmaceutical and healthcare industry and with the presence of pharmaceutical products and equipments,
                [membership] => 0
                [name] => Iphex
                [abbr_name] => Iphex
                [paid] => 0
                [event_wrapper] => 41539
                [event_samll_wrapper] => http://im.gifbt.com/industry/27-350x210.jpg
                [event_url] => iphex
                [website] => http://iphex-india.com/
                [eventType] => 1
                [venue_name] => Bombay Exhibition Centre
                [startDate] => 2015-05-13
                [endDate] => 2015-05-15
                [city] => Mumbai
                [country] => India
                [country_url] => india
                [country_shortname] => India
                [industry_id] => 27
                [industry_name] => Medical & Pharmaceutical
                [industry_url] => medical-pharma
                [event_status] => 
                [total_visitors] => 134
                [total_exhibitor] => 120
                [total_speakers] => 0
            )

            [2] => Array
            (
                [id] => 175534
                [des] => The TENSYMP, organized by the CimlGlobal will take place from 13th May to the 15th May 2015 at the Courtyard by Marriott, India in Ahmedabad, India. T
                [membership] => 
                [name] => TENSYMP Ahmedabad
                [abbr_name] => TENSYMP Ahmedabad
                [paid] => 
                [event_wrapper] => 
                [event_samll_wrapper] => http://im.gifbt.com/industry/40-350x210.jpg
                [event_url] => tensymp-ahmedabad
                [website] => http://www.tensymp2015.org/
                [eventType] => 2
                [venue_name] => Gujarat International Finance Tec-City
                [startDate] => 2015-05-13
                [endDate] => 2015-05-15
                [city] => Ahmedabad
                [country] => India
                [country_url] => india
                [country_shortname] => India
                [industry_id] => 40
                [industry_name] => Scientific Instruments
                [industry_url] => scientific-instruments
                [event_status] => 
                [total_visitors] => 3
                [total_exhibitor] => 0
                [total_speakers] => 3
            )

js码

      var desktop="/app.php/notificationdetail";
        var http = new XMLHttpRequest
        url = desktop,
        params = url;
        http.open("POST", url, !0), http.setRequestHeader("Content-type", "application/json; charset=UTF-8"), http.setRequestHeader("Content-length", params.length), http.setRequestHeader("Connection", "close"), 
        http.onreadystatechange = function() {
        if (4 == http.readyState && 200 == http.status) {


        var obj=http.responseText;
        alert(typeof obj);//string
        var parsed = JSON.parse(obj);



        for (var c in obj) {
        var newElement = document.createElement('div');
        newElement.id = obj[c]; newElement.className = "notification";
        newElement.innerHTML = obj[c];
        document.body.appendChild(newElement);
        } 
        }
        }, http.send(params);

问题

• 我需要找到数组的长度，比如如果使用php计数，那么它将显示2个数组，而如果在js中使用.length()，则不会返回所需的结果。

交货期应该是

• 通知中的计数应该是2使用javascript。
• 我需要在动态div中显示“id”、“name”、“city”。

我试过使用for循环

for (var x=0; x<obj.length; x++)
 {
   var name= obj[x].name;
    console.log(name);//outputs : undefined
 }

Answer 1

获取行数(对象计数)和列数(字段计数)的：

不熟悉w/ php Array，但在我看来，它是一个一维数组，每个数组元素都具有HashTable结构。

只是确认在您的console.log(parsed);行之后添加var parsed = JSON.parse(obj);。你应该看到类似[{id:50615,des:'PHARMA...',...},{id:57271,des:'The Iphex...',...},{...}]的东西。

如果是这样的话，parsed.length应该给出数据结构中对象(行)的数量，而Object.keys(parsed[0]).length将给出对象中的列/字段的数量。

注意__：这里唯一的事情是，我假设数组中的所有对象都有相同数量的字段。如果不是，您可能必须循环遍历数组，并计算数组中每个对象的最大长度，并将其用作列计数。

显示特定字段的：

一旦了解了对象数组的布局方式，就可以使用Array.map函数从原始数组中提取某些字段，如下所示：

var model = parsed.map(function(o) { return { id: o.id, name: o.name, city: o.city }; });

并使用现在应该只包含一个具有id、名称和city字段的对象数组的模型。

您似乎已经知道如何做DOM操作了，所以我不会去那里。我唯一能给出的建议是要么使用字符串连接并将其大容量注入DOM元素innerHTML，要么使用documentFragment方法来提高性能。请参阅：http://jsperf.com/concat-vs-docfrag/4