Retrieving individual fields from JSON file in Javascript

Question

im using backbone, jquery, underscore and i'd like to get at some JSON ive got in a local file.

Im currently using

        //Will get data but no access to individual objects
        $.getJSON('carinfo.json', function(data){
            console.log(data);
            var data2 = data['unitId'];
            console.log(data2);


        });

to pull the JSON into the data variable but i dont know where to go from here. How would i for instance get back all of the values from the field name 'carID'?

This is what one of my JSON entries looks like

{
    "carID": "xx",
    "xxx": {
        "unitID": "xxxxxxx",
        "positionHistory": [{
            "lat": "xxxxx",
            "long": "xxxxxxxx",
            "time": "xxxxxxxxxx",
            "status": "1",
            "estimatedSpeed": "0",
            "lastSoundFileName": "xxxxx",
            "lastSoundRange": "12",
            "lastSoundTime": "xxxxxxxx",
            "isToday": false,
            "minutesAgo": xxxxxx
        }]
    },
    "registration": "xxxxxxx",
    "color": "xxxxxxxx",
    "phone": "",
    "model": "xxxx"
}

Edit: using data.carID returns undefined.

Screenshot of chrome console output

enter image description here

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_Objects — Quentin, Jun 12 '13 at 16:03
data.carID etc returns undefined. I can log the entire thing and explore but i cant seem to get at the individual elements. — lorless, Jun 12 '13 at 16:10
possible duplicate of [Access / process (nested) objects, arrays or JSON](http://stackoverflow.com/questions/11922383/access-process-nested-objects-arrays-or-json) — Felix Kling, Jun 12 '13 at 16:22

Trevor Dixon · Answer 1 · 2013-06-12T18:05:31.377

Updated to account for the fact that your data is an array.

$.getJSON('carinfo.json', function (data) {
    // Loop over all the cars in data
    for (var i = 0; i < data.length; i++) {
        var car = data[i];
        car.carID === 'xx';  // just do data.whatever to get the value
        car.phone === '';

        car.xxx.positionHistory[0].status === '1'; // data.xxx.positionHistory is an array;
                                            // use [i] to get the ith element

        car.xxx['unitID'] === 'xxxxxxx';     // You can use bracket notation with a
                                      // string to get an object property if
                                      // you prefer

    }
});

score 0 · Answer 2 · answered Jun 12 '13 at 16:15

If your JSON is an array of car entries, then you need to access them as such:

$.getJSON('carinfo.json', function (data) {
    for(var i=0; i<data.length; i++) {
        console.log(data[i].carID);
    }

    // or access without a loop:
    console.log(data[0].carID);
    console.log(data[1].carID);
    console.log(data[0].xxx.unitID);
});

Retrieving individual fields from JSON file in Javascript

2 Answers2