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I'm having a really hard time trying to find a way to iterate through this JSON object in the way that I'd like. I'm using only Javascript here.

First, here's the object

{
"dialog":
{
    "dialog_trunk_1":{
        "message": "This is just a JSON Test"
    },

    "dialog_trunk_2":{
        "message": "and a test of the second message"
    },

    "dialog_trunk_3":
    {
        "message": "This is a test of a bit longer text. Hopefully this will at the very least create 3 lines and trigger us to go on to another box. So we can test multi-box functionality, too."
    }
}
}

Right now, I'm just trying basic ways to get through to each dialog_trunk on this object. I ideally want to loop through the object and for each trunk, display it's message value.

I've tried using a for loop to generate the name/number of the dialog_trunk on the fly, but I can't access the object using a string for the object name so I'm not sure where to go from here.

share|improve this question
    
You need a for..in loop –  bfavaretto Oct 11 '13 at 17:13
1  
possible duplicate of Access / process (nested) objects, arrays or JSON –  bfavaretto Oct 11 '13 at 17:13
1  
If possible, you should change your structure to use an ordered list. There's little sense in using a named key with an incrementing index. {"dialog":{"trunks":[{"message":"..."},{"message":"..."}]}} –  user2736012 Oct 11 '13 at 17:17
    
If it's JSON, have you parsed it? –  Andy Oct 11 '13 at 17:17
    
@dcp You're so useful, thank you. Perhaps next time I'll try to include that I couldn't find something similar enough to my own structure that I could figure out the proper way to go through. It's a shame that has to be explicitly stated these days. –  Eric Oct 11 '13 at 17:18

2 Answers 2

up vote 8 down vote

You use a for..in loop for this. Be sure to check if the object owns the properties or all inherited properties are shown as well. An example is like this:

var obj = {a: 1, b: 2};
for (var key in obj) {
  if (obj.hasOwnProperty(key)) {
    var val = obj[key];
    console.log(val);
  }
}

Or if you need recursion to walk through all the properties:

var obj = {a: 1, b: 2, c: {a: 1, b: 2}};
function walk(obj) {
  for (var key in obj) {
    if (obj.hasOwnProperty(key)) {
      var val = obj[key];
      console.log(val);
      walk(val);
    }
  }
}
walk(obj);
share|improve this answer
    
for..in is in the ECMAScript 1.0 specification. Even Internet Explorer 5 supports it.. (Source: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…) –  Roel van Uden Mar 27 at 22:47
up vote 1 down vote

My problem was actually a problem of bad planning with the JSON object rather than an actual logic issue. What I ended up doing was organize the object as follows, per a suggestion from user2736012.

{
"dialog":
{
    "trunks":[
    {
        "trunk_id" : "1",
        "message": "This is just a JSON Test"
    },
    {
        "trunk_id" : "2",
        "message": "This is a test of a bit longer text. Hopefully this will at the very least create 3 lines and trigger us to go on to another box. So we can test multi-box functionality, too."
    }
    ]
}
}

At that point, I was able to do a fairly simple for loop based on the total number of objects.

var totalMessages = Object.keys(messages.dialog.trunks).length;

    for ( var i = 0; i < totalMessages; i++)
    {
        console.log("ID: " + messages.dialog.trunks[i].trunk_id + " Message " + messages.dialog.trunks[i].message);
    }

My method for getting totalMessages is not supported in all browsers, though. For my project, it actually doesn't matter, but beware of that if you choose to use something similar to this.

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