javascript - json 数组可能时不时会丢失一个项目，如何将其设置为 0 并继续。也许是 isnull ？

Question

在我使用的天气数组中，只有下雨时才会出现雨。如果某个字段不在数组中，我该如何跳过该字段并继续前进？

$.ajax({
  type: 'GET',
  url: "http://api.openweathermap.org/data/2.5/forecast?lat="+latitude+"&lon="+longitude+"&units=imperial&APPID=removed",
  success: function(response) {
    icon = "wi-day-"+response.list[0].weather[0].main.toLowerCase();
    $('#city').html(response.city.name);
    $('#country').html(response.city.country);
    $('#current_temp').html(Math.round(response.list[0].main.temp)+' ºF');
    $('#weather_description').html(response.list[0].weather[0].description);
    $('#weather').html(response.list[0].weather[0].main);
    $('#max_temp').html(Math.round(response.list[0].main.temp_max)+' F');
    $('#min_temp').html(Math.round(response.list[0].main.temp_min)+' F');
    $('#humidity').html(response.list[0].main.humidity+' %');
    $('#rain_volume').html(response.list[0].rain[3h]+'"');
    $('#wind_speed').html(response.list[0].wind.speed+'MPH');

       console.log(response);
  }

});

我正在谈论的线路

 $('#rain_volume').html(response.list[0].rain[3h]+'"');

Answer 1

这只是一个避免所有 if 检查的示例。我个人不会使用它。但这只是一个想法

function always(obj){
  return new Proxy(obj, {
    get(target, prop) {
      if(target.hasOwnProperty(prop) && typeof target[prop] !== 'object'){
        return target[prop];
      }
      return always(target[prop] || {[Symbol.toPrimitive]:() => ''});
    }
  });
}
let response = {}; // some response
response = always(response);

// this line will not throw any error and will print an empty line
console.log(response.list[0].rain["3h"]+"");

response = {list:[{rain:{"3h":"test"}}]}; // some response
response = always(response);

// this line should print 'test'
console.log(response.list[0].rain["3h"]+"");