How to generate incremental variables with Javascript?

This may not be possible, if it is, it does not make up for the effort, the use of an array should be more practical.

var camadas = {};
for (var i = 0; i <= 20; ++i) {
    camadas["camada" + i] = 'Hello World ' + i;
}

To retrieve a value, simply specify the key camadaN , where N is the number in a range between 0 and 20 :

alert(camadas.camada5); // Hello World 5
//alert(camadas["camada5"]); // Sintaxe alternativa

To change the value of a key, do the following:

camadas.camada5 = "foo";
camadas.camada6 = "bar";
// Sintaxe alternativa
//camadas["camada5"] = "foo"; 
//camadas["camada6"] = "bar";

Exemplo

Update

According to this comment:

  

I am creating a web page, to caucular tensions on the ground, each   Soil layer has Height and Weight . I created an input that the   person types the number of layers. If the user types 5 for   example, 10 inputs will be generated, 5 for height and 5 for   Specific ... So for each layer I have to generate the variables   to do the calculations .... That's why I need to generate the   each layer ... I created them as objects, in the case a new layer I   I would only instantiate it, but I still have the same problem.

Use an array of arrays . Assuming it is necessary that each layer has specific height and weight, just do the following:

var camadas = {};
for (var i = 0; i <= 20; ++i) {
    camadas["camada" + i] = { 'altura': 'altura' + i,
                              'peso': 'peso' + i};
}

To retrieve the weight and height of a layer, simply specify the camadaN and the keys, in this case, altura and peso . Here's an example:

alert(camadas.camada1.altura); // Valor da altura da camada1
alert(camadas.camada20.peso);  // Valor do peso da camada20

Exemplo

Some ways follow below.

1) A global scope variable:

window['nomeDaVariavel'] = 1;
console.log(window.nomeDaVariavel); // Irá exibir o valor '1' no Console.

2) Compilation via eval:

eval("var variavel = 1");
console.log(variavel); // Irá exibir o valor '1' no Console.

But my suggestion would be to use arrays ( variavel[1] , variavel[2] , etc.) instead of dynamically declared variables. This makes handling the collection much easier.

The snippet below, in AngularJS, demonstrates this technique: The $scope.camadas property is initialized as an array (via $scope.camadas = [] ). Note after this the use of push (to add a new member), splice (to remove a member) and forEach (which allows iterating over all members of the array):

$myApp = angular.module('myApp',[]);

camadasCtrl = function($scope) {
  
  $scope.camadas = [];
  //        ^ inicializando o array
  $scope.peso = 0;

  $scope.addCamada = function() {
    $scope.camadas.push( {peso: $scope.peso } );
    //               ^ Adiciona um membro ao array
    
    calcTotal();

    
    $scope.peso = parseInt(Math.random() * 1000000) / 100;
  }
  $scope.delCamada = function(index) {
    $scope.camadas.splice(index, 1);
    //               ^ Remove um membro do array
    
    calcTotal();
  }
  
  var calcTotal = function() {
    
    var total = 0;
    
    $scope.camadas.forEach(function(item) {
    //                ^ Para cada membro do arry, o código a seguir é executado
        total += item.peso;
    });
    
    $scope.pesoTotal = total;
  }
}

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script><divng-app='myApp'><divng-controller='camadasCtrl'>Peso:<inputtype='text'ng-model='peso'><buttonng-click='addCamada()'>AdicionarCamada{{camadas.length}}</button><divng-repeat='camadaincamadas'><buttonng-click='delCamada($index)'>Remover</button>Camada{{$index}}:{{camada.peso}}Kg</div>PesoTotal:{{pesoTotal}}</div></div>

Theresultisasfollows: