javascript - 如何使用 jQuery 访问 json 文件中的这些键和值？

Question

我在访问 json 文件中的键和值时遇到问题。我已经尝试了很多事情，但这周我的注意力集中在我身上，但我陷入了困境。

这是我的 Transport.json 文件..

{"transportation":[
    {"Springfield":[{
        "bus":[{
            "start": 6,
            "end": 24,
            "stops":["oak street", "main street"]
        }],
        "taxi":[{
            "start": 25,
            "end": 25,
            "stops":["all"]
        }]
    }]},
    {"Pleasantville":[{
        "bus":[{
            "start": 6,
            "end": 22,
            "stops":["centre street", "river street"]
        }],
        "taxi":[{
            "start": 25,
            "end": 25,
            "stops":["all"]
        }],
        "train":[{
            "start": 6,
            "end": 23,
            "stops":["uptown", "downtown"]
        }]
    }]}
]}

我想做的两件事是..

1. 我希望能够提醒用户当前区域的总线起始值。

2. 我想循环遍历公交车站点以与用户当前站点进行比较。

这是我的 js 代码..

var currentArea = 'Pleasantville'; // this variable changes
var currentStop = 'uptown'; // this variable changes
$.getJSON("transport.json", function(jsontransportation) {
    $(jsontransportation.transportation).each(function(dataaaa) {
        var areaName = Object.keys(this);
        if (areaName == currentArea) { // this works to find correct area in json
            $(this.bus).each(function(key, value) { // i can't get this loop to work
                alert(this.start); // alerts nothing, no errors
                $(this.stops).each(function(key) { // now im trying to loop through keys in 'stops'
                    if (this.key === currentStop) { // to compare stop to current area
                        alert('the bus stops here at ' + currentStop); // and alert if there is a stop here
                    } else {
                        alert('the bus does not stop here at ' + currentStop); // else alert no stop here
                    }
                })
            });
        }
    });
});

Answer 1

这正是您所需要的。我还更改了代码，以便警报仅显示一次。

$(document).ready(function(){
   var currentArea = 'Pleasantville'; // this variable changes
   var currentStop = 'uptown'; // this variable changes
  $.getJSON("transport.json", function(jsontransportation) {
      $(jsontransportation.transportation).each(function(dataaaa) {
          var areaName = Object.keys(this);
          if (areaName == currentArea) { 
             var selectedArea = this[currentArea];
             var bus = selectedArea[0].bus;
             var stops;
             $(bus).each(function(keyBus, valueBus) { 
               alert(this.start); 
               stops = false;
               $(this.stops).each(function(key, valueStops) { 
                      if (valueStops === currentStop) { 
                          stops = true;
                      } 
                  })
             });
             if(stops){
                alert('the bus stops here at ' + currentStop); 
             }else{
                alert('the bus does not stop here at ' + currentStop); // else alert no stop here
             }


          }
      });
  });
});

要解决此问题，请访问 PLUNKR 的链接。