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如何使用 Javascript 检索实时数据库中的值?

[英]How to retrieve a value in Realtime Database using Javascript?

I don´t have a lot of programming experience, and I´m trying to solve the following: Given this data structure using Realtime Database Data Structure I want to show in an HTML table the value of the "propina" key, but not the identifier that the Realtime Database generates.我没有很多编程经验,我正在尝试解决以下问题:鉴于此数据结构使用实时数据库数据结构,我想在 HTML 表中显示"propina"键的值,而不是实时数据库生成的标识符。

Up until now, I´m running this code to retrieve the values of the data:到目前为止,我一直在运行这段代码来检索数据的值:

` `

    var database = firebase.database();     

    database.ref().once('value', function(snapshot){

         if(snapshot.exists()){

             var content = '';

             snapshot.forEach(function(data){

                 var val = data.val();

                 content +='<tr>';

                 content += '<td>' + val.nombre + '</td>';

                 content += '<td>' + val.lugar + '</td>';

                 content += '<td>' + val.ubicacion + '</td>';

                 content += '<td>' + val.propina + '</td>';

                 content += '</tr>';

             });

             $('#ex-table').append(content);

         }

     });`

But the " propina" value is not displayed, giving me just \[object Object\] in the HTML.但是没有显示“ propina"值,只给我 HTML 中的\[object Object\]

The issue is that propina is an object , not a string or a number .问题是propinaobject ,而不是字符串数字 You need to access its value .您需要访问它的 You can access the value like this:您可以像这样访问值:

  ...

  content += '<td>' + val.propina.value + '</td>';

  ...

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