JS parsing JSON. Undefined error when its defined

Question

This is a JSON code that is generated on the server side and sent through websockets to the client as a string:

{
    "zw_ob-k7g8ahcvFzAAAA":{
        "position":{  
             "x":319,
             "y":135
        },
        "mass":324,
        "name":21,
        "color":"#5058a9"
    },
    "uTFD8dw0OiqD4ErzAAAB":{
        "position":{  
            "x":473,
            "y":348
        },
        "mass":59,
        "name":7,
        "color":"#e79448"
    },
    "CvMRJ6rEFYoU1vajAAAC":{
        "position":{  
            "x":25,
            "y":604
      },
        "mass":147,
        "name":18,
        "color":"#cef6c3"
    },
    "_e6TLrfubHqf-7esAAAD":{
        "position":{  
            "x":146,
            "y":417
        },
        "mass":320,
        "name":13,
        "color":"#ab7aa0"
    }
}

On the client I use JSON.Parse to parse this string into json structure.

planetsData = JSON.parse(data.planets);

for(var p in planetsData){

    var playerName = p;
    alert(p.position) //says "undefined" 
    var planetColor = p.color;
    var planetName = p.name;

    var planet = new Planet();
}

I can successfully get p, p.color and p.name, but for some reason it says that p.position is undefined, hence I can't access p.position.x or p.position.y parameters.

@AlbertoTrindadeTavares console.log P works. Outputs the key — Nick
– Nick, Commented Oct 13, 2018 at 13:37

Hassan Sadeghi · Accepted Answer · 2018-10-13 13:44:02Z

4

Change this line alert(p.position) to this:

 alert(planetsData[p].position);

And for other usages too.

Also you can add this:

p=planetsData[p];

At first of loop and now use your code itself:

for(var p in planetsData){
   var playerName = p;

   p=planetsData[p]; //add this line here

   alert(p.position) ;
   var planetColor = p.color;
   var planetName = p.name;

   var planet = new Planet();
 }

edited Oct 13, 2018 at 13:44

answered Oct 13, 2018 at 13:39

Hassan Sadeghi

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1 Comment

Hassan Sadeghi Over a year ago

You're welcome @Nick :) I'm glad that helped you. You can mark the answer as accepted if it was useful.

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