如何遍历JavaScript数组/对象

Question

I am having a hard time trying to get my data from this array. Can someone please tell me how to do this?

I need to get the latLng and AdminArea4 from within the locations for an autocomplete.

Can someone please explain the difference between the {} and [] . From what I know, one is an array and the other an object but I am not sure if this is right. Is the process different from traversing an array than an object?

{
   "results": [
      {
         "locations": [
            {
               "latLng": {
                  "lng": 24.873108,
                  "lat": 59.389755
               },
               "adminArea4": "Harju maakond",
               "adminArea5Type": "City",
               "adminArea4Type": "County",
               "adminArea5": "Rae vald",
               "street": "",
               "adminArea1": "EE",
               "adminArea3": "",
               "type": "s",
               "displayLatLng": {
                  "lng": 24.873108,
                  "lat": 59.389755
               },
               "linkId": 0,
               "postalCode": "",
               "sideOfStreet": "N",
               "dragPoint": false,
               "adminArea1Type": "Country",
               "geocodeQuality": "CITY",
               "geocodeQualityCode": "A5XXX",
               "adminArea3Type": "State"
            },
            {
               "latLng": {
                  "lng": 24.860184,
                  "lat": 59.38493
               },
               "adminArea4": "Harju maakond",
               "adminArea5Type": "City",
               "adminArea4Type": "County",
               "adminArea5": "Rae",
               "street": "",
               "adminArea1": "EE",
               "adminArea3": "",
               "type": "s",
               "displayLatLng": {
                  "lng": 24.860184,
                  "lat": 59.38493
               },
               "linkId": 0,
               "postalCode": "",
               "sideOfStreet": "N",
               "dragPoint": false,
               "adminArea1Type": "Country",
               "geocodeQuality": "CITY",
               "geocodeQualityCode": "A5XXX",
               "adminArea3Type": "State"
            },
         ]
      }
   ]
}

Answer 1

First some explanation about arrays and objects since you've asked and it's quite relevant to how to use the data structure you have:

{} defines an object. [] defines an array.

An object is a unordered list of property/value pairs with no property name repeated.

An array is an ordered list of individual items with a .length property that tells you how many items are in the array.

---

An object would be defined like this:

var obj = {
   prop1: value1,
   prop2: value2
};

And, you can reference values like this:

console.log(obj.prop1);    // value1

An array is defined like this:

var myArray = ["one", "two", "three"];

And, you can access elements by zero-based index like this:

console.log(myArray[0]);   // "one"

Or, you can iterate all the items in an array like this:

for (var i = 0; i < myArray.length; i++) {
    console.log(myArray[i]);
}

---

Assuming your overall data structure is in a variable named data , you can iterate the results and nested locations arrays like this:

var results = data.results;
var locations;
for (var j = 0; j < results.length; j++) {
    locations = results[j].locations;
    for (var i = 0; i < locations.length; i++) {
       console.log(locations[i].latLng);
       console.log(locations[i].adminArea4);
    }

To explain:

1. data.results is an array that you need to iterate.
2. In each element of that array is an object with a locations property in it.
3. The locations property is another array that you need to iterate.
4. In each element of the locations array is an object with a latLng property and a adminArea4 property on it.

Answer 2

It's json structure.. You can access elements as I mentioned below.. Assign json to variable and then access object properties.

var obj = {
   "results": [
      {
         "locations": [
            {
               "latLng": {
                  "lng": 24.873108,
                  "lat": 59.389755
               },
               "adminArea4": "Harju maakond",
               "adminArea5Type": "City",
               "adminArea4Type": "County",
               "adminArea5": "Rae vald",
               "street": "",
               "adminArea1": "EE",
               "adminArea3": "",
               "type": "s",
               "displayLatLng": {
                  "lng": 24.873108,
                  "lat": 59.389755
               },
               "linkId": 0,
               "postalCode": "",
               "sideOfStreet": "N",
               "dragPoint": false,
               "adminArea1Type": "Country",
               "geocodeQuality": "CITY",
               "geocodeQualityCode": "A5XXX",
               "adminArea3Type": "State"
            },
            {
               "latLng": {
                  "lng": 24.860184,
                  "lat": 59.38493
               },
               "adminArea4": "Harju maakond",
               "adminArea5Type": "City",
               "adminArea4Type": "County",
               "adminArea5": "Rae",
               "street": "",
               "adminArea1": "EE",
               "adminArea3": "",
               "type": "s",
               "displayLatLng": {
                  "lng": 24.860184,
                  "lat": 59.38493
               },
               "linkId": 0,
               "postalCode": "",
               "sideOfStreet": "N",
               "dragPoint": false,
               "adminArea1Type": "Country",
               "geocodeQuality": "CITY",
               "geocodeQualityCode": "A5XXX",
               "adminArea3Type": "State"
            },
         ]
      }
   ]
};

Travsering Values

obj.results[0].locations[0].latLng.lng
obj.results[0].locations[0].latLng.lat

You can also traverse by using for loop.