Find end of $.each() loop

Question

I need to find the end of a loop or the length of the object. Some context on the code:

I obtain the txt var from the DOM (that's the only way I've got by now and can't change it) and it's a formatted JSON. Here's an example of the expected JSON output:

{"SE DIO AVISO A CENTRAL":true,"OTRO":false,"SE DIO AVISO A SEGURIDAD CIUDADANA":true,"SIN ACCIÓN":false,"SE DIO AVISO A AMBULANCIA":false,"SE DIO AVISO A CARABINEROS":true,"SE DIO AVISO A BOMBEROS":false}

My idea here is to only show the ones with value trueone after the other followed by a comma, but changing that at the end of the loop for a dot. For the moment I've got the commas down but not the dot, which is why I need to know either the length of obj or the end of the $.each() loop. Any improvements on overall code are appreciated.

try{
    var obj=jQuery.parseJSON(txt);
    $(self).text(" ");
    var i = 0;
    jQuery.each(obj, function(text, val){
        if(val){
            if(i == 0){
                $(self).append(text);
            }else{
                $(self).append(", "+text);
            }
        }
        i++;
    });
}
catch(e){
}

Answer 1

You can do this with jQuery.map extremely elegantly as the function allows you to do a filtered map (.map excludes any item when you return null or undefined). As $.map produces an array you can then just use Array.prototype.join and get the same output as our original code. If you want to add a period to the string after that then you can check if your string isn't empty, append a period and be on your way.

var text = $.map(obj, function(val, key) { if(val) return key; } ).join(", "); //Create an array of an objects keys where its value is truthy. Next, join the keys.
if(text !== "") text += "."; // Append a period if not an empty string

$(self).append(text);

Also you should reconsider using a try catch block around the JSON parsing as you shouldn't expect that to fail without good reason.

Answer 2

You are basically mimicking the behavior of join here. Simply collecting the correct values into an array and then joining these values will be simpler.

This is what I would counter-propose:

try{
  var o = jQuery.parseJSON( s ),
      keys = [];
  jQuery.each(o, function(key, value){
    if(value){
      keys.push(key);
    }
  }
  $(self).text( " " + keys.join(",") + "." );
}
catch(e){
}