How to populate associative array through for loop

Question

I need to create this kind of element inside my array:

{ Field1: "2011/04/23", Field2: 8, Field3: "Adam", Field4: "Den"},  
{ Field1: "2011/03/25", Field2: 6, Field3: "Honey",Field4: "Singh"}

How may I increasce that field1 counter ?

var resultado = [];
    for(i=0;  i< dados.length; i++){                
        resultado[i] = { "Field"+i: dados[columns[i]]};
    }

If I try to do like above, it gives me an error saying I can't use the + character. How may I achieve my goal ?

Obs: i'll not always have 4 fields, it may vary.

UPDATE

Following the answers I could achieve part of what I need, now the code is like this:

var resultado = [];
    for(i=0;  i< dados.length; i++){                
        resultado[i] = { ["Field"+i]: dados[columns[i]]};
    }

But I'm not managing to write all of that in a single position of the array.
How may I get this:

var results = [
      {
       Field1: "2011/04/23",
       Field2: 8,
       Field3: "Adam",
       Field4: "Den"  
      }, //First Element  

      {
       Field1: "2011/03/25",
       Field2: 6,
       Field3: "Honey",
       Field4: "Singh"  
      } //Second Element
    ];

I'm using JqueryDataTable, so I need to create an obj to populate it dinamically.

I have an ajax that returns me a Json with the name of the columns.

["id_localidade","cod_munic","id_bairro","id_endereco"]  
//These are column names that I need to use later.

Then I have another Ajax to bring me the DATA from this same table as a Json:

[  
{"id_bairro":"1","dsc_bairro":"PONTE DOS CARVALHOS"},  
{"id_bairro":"2","dsc_bairro":"CHARNECA"},  
{"id_bairro":"3","dsc_bairro":"SAO FRANCISCO"},  
{"id_bairro":"4","dsc_bairro":"ROSARIO"}  
]

So now I need to use these two arrays and create the this:

{ Field1: "2011/04/23", Field2: 8, Field3: "Adam", Field4: "Den"},

Where Field1, Field2, FieldN will depend on how many columns the selected column has. (As I have the name of those columns I just need to count it).

What I tried so far (without success):

var nFields   = Object.keys(dados[0]).length;//Number of columns
var nElements = dados.length; //Number of registers

var resultado = [];
for(i=1;  i<= nElements; i++){
   for(j=0; j < nFields; j++){
      var temp = [];
      temp.push({ ["Field"+ (j+1)]: dados[j][ columns[j]['sTitle'] ] });
      resultado = temp;
   }                
}

guest271314 · Accepted Answer · 2016-12-04 19:37:12Z

1

You can use brackets to produce a computed name for a property of an object.

Obs: i'll not always have 4 fields, it may vary.

If dados array is an array of arrays, utilize nested for loop to iterate each element of current dados[i] array.

var dados = [
  [0, 1, 2],
  [3, 4],
  [5, 6, 7, 8]
];
var resultado = [];
var prop = "Field";
for (var i = 0; i < dados.length; i++) {
  resultado[i] = {};
  for (var n = 1; n < dados[i].length; n++) {
    resultado[i][prop + n] = dados[i][n - 1];
  }
}

console.log(resultado);

edited Dec 4, 2016 at 19:37

answered Dec 4, 2016 at 19:03

guest271314

1

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4 Comments

PlayHardGoPro Over a year ago

And how may I create all of those: Field1: "", Field2: "". I'm having dificult to insert all of the necessary fields in a single row of the object dinamically

guest271314 Over a year ago

@PlayHardGoPro Have you tried stacksnippets? Created example dados array of arrays which have variable .length. At inner for loop iterate each element of inner array. The property name of the object should be incremented beginning at "Field1", where n at inner loop is initially set to 1. Note the n-1 within bracket at dados[i][n - 1]. Which portion of javascript at Answer are you experiencing difficulties utilizing?

guest271314 Over a year ago

@PlayHardGoPro Is dados the array of objects?

PlayHardGoPro Over a year ago

Worked what you said. I just took a better look and it's running like a boss. I'll post the answer aswell.

Dekel · Accepted Answer · 2016-12-04 19:02:09Z

1

Just as a note - in javascript they are not called associative arrays, they are just objects.

option1:

You can create an empty object, and then add the key using obj[key]:

var resultado = [];
for(i=0;  i< dados.length; i++){                
    resultado[i] = {};
    resultado[i]["Field"+i] = dados[columns[i]]
}

option2:

You can create the name of the key before using it:

var resultado = [];
for(i=0;  i< dados.length; i++){                
    key = "Field"+i
    resultado[i] = {key: dados[columns[i]]};
}

answered Dec 4, 2016 at 19:02

Dekel

62.9k12 gold badges109 silver badges130 bronze badges

2 Comments

PlayHardGoPro Over a year ago

And how may I create all of those: Field1: "", Field2: "". I'm having dificult to insert all of the necessary fields in a single row of the object dinamically

Dekel Over a year ago

A bit hard to help because I don't know the content of columns and dados. Add them to the question

Nina Scholz · Accepted Answer · 2016-12-04 19:04:16Z

1

You could use a default object, if resultado[i] is not set and use bracket notation for the access.

resultado[i] = resultado[i] || {};
resultado[i]["Field" + i] = dados[columns[i]];

answered Dec 4, 2016 at 19:04

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Comments

mitch · Accepted Answer · 2016-12-04 19:02:00Z

0

Just use push method.

var resultado = [];
for(var i=0;  i< dados.length; i++){                
    resultado.push({ "Field"+i : dados[columns[i]]});
}

answered Dec 4, 2016 at 19:02

mitch

2,2454 gold badges28 silver badges46 bronze badges

2 Comments

mitch Over a year ago

There is no just var improvement. See it again.

PlayHardGoPro Over a year ago

Thanks man. But I already tried that I just changed to see if for some miracle reason it would work this way.

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