Generate Dynamic Array of Object in javascript

Question

My Javascript code is:

neighborhoods = [
  {lat: 52.511, lng: 13.447},
  {lat: 52.549, lng: 13.422},
  {lat: 52.497, lng: 13.396},
  {lat: 52.517, lng: 13.394}
];

I want to generate this array dynamically in java script itself. Means values are dynamic, keys are static i.e "lat", "lng". U can take it like I want to generate this array inside one loop. example:

    for (int i=0;i<5;i++){
      val1=1, val2=2;
     
   //  here generate this array using above value
    val1 = val1+1; val2=val+1;

    }

This is just example.. I hope requirement is clear now.. Please help

jfriend00 · Accepted Answer · 2015-08-22 17:26:24Z

2

You can create an array and then put objects with properties in it like this:

var neighborhoods = [];
neighborhoods.push({lat: 52.511, lng: 13.447});

Or, if your lat, lng values are in variables so you want to build the objects dynamically, you can do this:

var neighborhoods = [];
var obj = {};
obj.lat = lat;
obj.lng = lng;
neighborhoods.push(obj);

And, if you had a source of lat, lng data that you could iterate with a for loop, you could just put the object creation and .push() into a for loop.

For example, if you had an array of alternating lat,lng values, you could do this:

var values = [52.511, 13.447, 52.549, 13.422, 52.497, 13.396, 52.517, 13.394];
var neighborhoods = [];
for (var i = 0; i < values.length; i+=2) {
    neighborhoods.push({lat: values[i], lng: values[i+1]});
}
document.write(JSON.stringify(neighborhoods));

edited Aug 22, 2015 at 17:26

answered Aug 22, 2015 at 16:03

jfriend00

711k104 gold badges1.1k silver badges1k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Abhishek Singh Over a year ago

if I see "neighborhoods" value on alert. it shows [object,object],[object][object].... while if I aler static neighborhoods = [ {lat: 52.511, lng: 13.447},...{..}]; this shows exact value, as it is,not [object.] why this differeence in both

jfriend00 Over a year ago

@AbhishekRajawat - just run the last code snippet and it will show you the values are properly in there. alert() is not a valid diagnostic tool for looking at multi-level data structures in pretty much any way. You can use console.log() and then look in the debug console for the actual data. Or, you should learn the debugger where you can directly inspect the contents of any variable in scope.

charlietfl · Accepted Answer · 2015-08-22 16:04:27Z

1

it's not entirely clear how the calculations or values need to be derived but a simple example would be:

var lat = 52, lng = 13;
var neighborhoods = [];

 for (int i=0;i<5;i++){
      lat += 1;
      lng += .1; 
      neighborhoods.push({lat: lat , lng : lng })
}

answered Aug 22, 2015 at 16:04

charlietfl

172k14 gold badges125 silver badges154 bronze badges

2 Comments

Abhishek Singh Over a year ago

this is correct. but the problem is if i see its value on Alert(), why it shows [object,object],[object..]. Instead if I display/Alert my static "neighborhoods" it shows [ {lat:1, lng:1},{..} ] . why this d/f, I dont want object

charlietfl Over a year ago

array structures are identical . You must be altering a stringified version of the first one. Using alert is not a good debugging tool, use console logging methods instead

Ahmed Gamal · Accepted Answer · 2015-08-22 16:13:07Z

1

You are very close. First of all, if you wish to use the array subscript notation, you have to pass the keys themselves (strings in your case, like this):

    var myAssociativeArr = [];
  for (var i=0; i < 5; i++) {
   var newElement = {};
newElement['id'] = val1;
newElement['lname'] = val2;
newElement['fname'] = val3;
myAssociativeArr.push(newElement);
  }

Where the key names are known strings, it's often preferable to use the completely equivalent notation of object properties:

var myAssociativeArr = [];
 for (var i=0; i <5; i++) {
var newElement = {};
newElement.id = val1;
newElement.lname = val2;
newElement.fname = val3;
myAssociativeArr.push(newElement);
 }

answered Aug 22, 2015 at 16:13

Ahmed Gamal

1,7061 gold badge17 silver badges25 bronze badges

Collectives™ on Stack Overflow

Generate Dynamic Array of Object in javascript

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related