How to iterate over json array in javascript

Question

Yes there are many post regarding this.But my doubt is little different.I have following array for example

var dictionary = {
    "12Jan2013": [{
        "id": "0",
        "name": "ABC"
    }, {
        "id": "1",
        "name": "DEF"
    }],
    "13Jan2013": [{
        "id": "0",
        "name": "PQR"
    }, {
        "id": "1",
        "name": "xyz"
    }]
};

Same post is there on same site BUT here in dictionary json array key is dynamic.Here it is date ie 12Jan2013.It can be any date.It is not static.I have searched for that but didn't get solution.

How to iterate over such a json array?

AND How to print json array as in same formate shown above?

EDIT

Here is my real code.And i shown a comment in following code where i wanted to iterate data ie jsonData var in getWeatherDataForCities callback

var arrAllrecords = [];
var arrCityrecordForADay = [];
function getWeatherDataForCities(cityArray, callback){

var toDaysTimestamp = Math.round((new Date()).getTime() / 1000) - (24*60*60);
for(var i in cityArray){

    for(var j=1; j<=1; j++){
        var jsonurl = "http://api.openweathermap.org/data/2.5/history/city?q="+cityArray[i]+"&dt="+toDaysTimestamp;

        $.ajax({
            url: jsonurl,
            dataType: "jsonp",
            mimeType: "textPlain",
            crossDomain: true,
            contentType: "application/json; charset=utf-8",
            success: function(data){                    
                var arrCityRecordForDay = [];
                /*arrCityrecordForADay.push(data.list[0].city.name);
                arrCityrecordForADay.push(data.list[0].weather[0].description);
                arrCityrecordForADay.push(timeConverter(data.list[0].dt));
                arrCityrecordForADay.push(data.list[0].main.temp);
                arrCityrecordForADay.push(data.list[0].main.humidity);
                arrCityrecordForADay.push(data.list[0].main.pressure)
                arrCityrecordForADay.push(data.list[0].wind.speed);*/
                //'{"pets":[{"name":"jack"},{"name":"john"},{"name":"joe"}]}';

                arrCityRecordForDay.push(
                    {"cityName" : data.list[0].city.name},
                    {"weather" : data.list[0].weather[0].description}
                );

                var tempId = data.list[0].city.name+"-"+timeConverter(data.list[0].dt);

                arrCityrecordForADay.push(
                    {tempId : arrCityRecordForDay}
                );

                if(((arrCityrecordForADay.length)) === cityArray.length) {
                    callback(arrCityrecordForADay);
                }

        } });
        toDaysTimestamp = toDaysTimestamp - (24*60*60);
    }   
}       
}

$(document ).ready(function() {

 var cityArray = new Array();
  cityArray[0] = "pune";

  getWeatherDataForCities(cityArray, function(jsonData) {
        // Here I want to iterate jsonData
  });


});

Answer 1

Use for-in...something like:

for (var i in dictionary) {
    dictionary[i].forEach(function(elem, index) {
        console.log(elem, index);
    });
}

where the i would iterate through your dictionary object, and then you can use forEach for every json array in the dictionary(using dictionary[i])

With this code you'll get

Object {id: "0", name: "ABC"} 0 
Object {id: "1", name: "DEF"} 1 
Object {id: "0", name: "PQR"} 0 
Object {id: "1", name: "xyz"} 1 

You can tailor the forEach function definition(replacing the console.log bit) to do whatever you want with it.

DEMO

Edit: Doing the same thing using Object.keys

Object.keys(dictionary).forEach(function(key) {
    dictionary[key].forEach(function(elem, index) {
        console.log(elem, index);
    });
});

Edit2: Given the somewhat complicated structure of your jsonData object, you could try using a (sort of) all-purpose function that would act on each type of component separately. I've probably missed a few cases, but maybe something like:

function strung(arg) {
    var ret = '';
    if (arg instanceof Array) {
        arg.forEach(function(elem, index) {
            ret += strung(elem) + ',';
        });
    } else if (arg instanceof Object) {
        Object.keys(arg).forEach(function(key) {
            ret += key + ': /' + strung(arg[key]) + '/';
        });
    } else if (typeof arg === "string" || typeof arg === "number") {
        ret = arg;
    }
    return ret;
}

document.body.innerHTML = strung(jsonData);

DEMO

Answer 2

Please note that yours is just a JavaScript array object. To make it simple to understand, you can iterate over it like this:

for (var i in dictionary) {
    // do something with i
    // here i will contain the dates

    for (n = 0; n < dictionary[i].length; n++) {
        // do something with the inner array of your objects    
        // dictionary[i][n].id contains the "id" of nth object in the object i
        // dictionary[i][n].name contains the "name" of nth object in the object i
    }
}

See this fiddle: http://jsfiddle.net/Ke8F5/

The iteration looks like this:

12Jan2013 : (id = 0, name = ABC) (id = 1, name = DEF)  
13Jan2013 : (id = 0, name = PQR) (id = 1, name = XYZ)

Answer 3

You can use a for loop.

for (var i in json) {
 ...
}

Then, i is the current key, so, you can acess json[ i ] and get the data to the corresponding index.

And then, if you need to iterate over inner elements, you can do the same thing.

Answer 4

You can use for ... in but you should combine it with hasOwnProperty or you'll find yourself iterating over inherited properties likely breaking your code.

  for (var key in object) {
    if (object.hasOwnProperty(key)) {
        // Do stuff.
    }
  }