CODEWITHSUNDEEP
javascriptarraysjson
Nico
Nico

Reputation: 31

Populate JSON with javascript array and modify entry

Modifying a JSON array (nested into another array) seems NOK with this code:

   var names = [{'name': 'ourname'},{'name': 'yourname'}] ;

    var array = [{
        "year": "2015",
        names
      },{
        "year": "2016",
         names
      }];

I can't modify a single name entry in "array" by doing this

array[0].names[1].name="MY NAME"

since it's actually modifying all names entry in the row "0":

Output:

0:0 ourname
0:1 MY NAME
1:0 ourname
1:1 MY NAME

Plunker here

I'm looking for a clean way to achieve a proper single modification in the name array as I'd like to avoid loops to do this.

Thanks for your help

Upvotes: 2

Views: 69

Answers (3)

Rodrigo Vargas
Rodrigo Vargas

Reputation: 75

You need a key: value in an object (javascript object).

var names = [{'name': 'ourname'},{'name': 'yourname'}] ;

var array = [{
        "year": "2015",
        "names": names
      },{
        "year": "2016",
        "names": names
      }];
var wName = array[0].names[1].name;
// yourname

Upvotes: 0

fuyushimoya
fuyushimoya

Reputation: 9813

Because they're pointing to same array, and also, simply clone names by .slice is not enough, as the array contains objects not primitive types, so you need to deep clone from the original names and assign to each object. So you need to change the code to :

var array = [{
  "year": "2015",
  names: JSON.parse(JSON.stringify(names))
}, {
  "year": "2016",
  names: JSON.parse(JSON.stringify(names))
}];

See the edited pluker.

I use JSON.parse(JSON.stringify(names)) to simply create do deep clone from original array here, there can have other ways.

Upvotes: 2

Michael Tang
Michael Tang

Reputation: 4916

You should try copying the names array, once for each "unique" use case, since Javascript sneakily has references sometimes.

One way to do it is to write a deepclone() method that will do a deep copy of a hierarchical object.

var array = [{
    "year": "2015",
    names: deepclone(names)
},{
    "year": "2016",
    names: deepclone(names)
}];

Upvotes: 0

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