Loop in function by calling itself

Question

Loop in function by calling itself

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#1 by (6 votes)
#2 by (1 votes)

3

I need to create a purposeful loop to check if a variable has reached the desired value, the idea is to create a function that inside it will have a if , which verifies if cont == 4 in case 4 is the number of iterations previous to function, if it continues the process if it is not yet 4 it gives a setInterval passing by parameter to função in 500 milissegundos .

Below the code:

      function verificaCont(){

        if(data.cont == 4){
          console.log(data);
        }else{
          setInterval(verificaCont(), 500); 
        }

      }

The error that occurs when executing this function is:

Uncaught SyntaxError: In strict mode code, functions can only be declared at top level or immediately within another function.

How can I solve this problem? or is there something for me to have to generate a loop?

REASON:
I need this loop because I'm doing an activity that wants to save in a multiple data object, between these data it may be necessary to go to the database, however the bank used is asynchronous, so I need a loop to give it time to fill the whole object.

javascript jquery

asked by anonymous 01.10.2015 / 16:21

2 answers

6

setInteval is a function that performs a particular / strong> in a time interval.

If you want to do this, you should use setTimeout that only runs once after the break.

Code

function verificaCont(){
    if(data.cont == 4){
        console.log(data);
    }else{
        setTimeout(function(){
            verificaCont();
        }, 500);
    }
}

Alternative

function verificaCont(){
    this.checkCount = setInterval(function(){ 
        if(data.cont == 4){
            clearInterval(this.checkCount);
        }
    }, 500);
}

01.10.2015 / 16:35

Analysis and correction of connection test errors using DB using hibernate How to put it right in the header?

score 1 · Accepted Answer

As I said, it's to give you a complete answer, it would be interesting if you put your code with IndexedDB, so I'll just post a generic answer.

For example, let's imagine two Tables, Users and People, where Users have a 1: N relationship with People and we just want the User Login and Person Name.

var transaction = db.transaction(["usuarios", "pessoas"]);
var usuarioStore = transaction.objectStore("usuarios");
var pessoaStore = transaction.objectStore("pessoas");

var UsuarioModel = function(usuarioID, callback) {
  var self = this;
  self.UsuarioID = usuarioID;

  var usuarioRequest = usuarioStore.get(self.UsuarioID);
  usuarioRequest.onsucess = function (event) {
    self.Logon = usuarioRequest.result.Logon;

    var pessoaRequest = pessoaStore.get(usuarioRequest.result.PessoaID);
    pessoaRequest.onsucess = function (event) {
      self.Nome = pessoaRequest.result.Nome;
      callback();
    }
  }    
}

var usuarioModel = new UsuarioModel(35, function () {
  console.log(usuarioModel);
});

In the above example, the function of callback will be executed Name is retrieved.

Now let's imagine a second scenario, the entity Users and People are independent, but need to wait for the return of the two requests to execute some code.

var transaction = db.transaction(["usuarios", "pessoas"]);
var usuarioStore = transaction.objectStore("usuarios");
var pessoaStore = transaction.objectStore("pessoas");

var UsuarioModel = function(usuarioID, pessoaID, callback) {
  var self = this;
  var sucessos = 0;
  var execCallBack = function () {
    sucessos++;
    if (sucessos == 2) {
      callback();
    }
  } 

  self.UsuarioID = usuarioID;
  self.PessoaID = pessoaID;

  var usuarioRequest = usuarioStore.get(self.UsuarioID);
  usuarioRequest.onsucess = function (event) {
    self.Logon = usuarioRequest.result.Logon;
    execCallBack();
  }    

  var pessoaRequest = pessoaStore.get(self.PessoaID);
  pessoaRequest.onsucess = function (event) {
    self.Nome = pessoaRequest.result.Nome;
    execCallBack();
  }
}

var usuarioModel = new UsuarioModel(35, 58, function () {
  console.log(usuarioModel);
});