AJAX overwrites variable

Question

I cannot copy the result to the variable registroJson, I’ve already lost almost a day in this trouble:

$(document).ready(function(){

  var registroJson = [];
  var url = 'xpto';  

  $.getJSON(url,function(data){

    registroJson = data; //copiando para variavel registroJson o resutado 'data' 

    // já tentei registroJson.push(data) e tabem não funciona    
  }); 

  console.log(registroJson); //o resultado no console sempre mostra [], array vazio

});

Answer 1

Ajax is asynchronous and non-synchronous, which rotates within (is a callback):

  function(data){

    registroJson = data; //copiando para variavel registroJson o resutado 'data' 

    // já tentei registroJson.push(data) e tabem não funciona    
  }

It is only fired later because you need the request to finish first, already the console.log is fired before because it is outside the callback and you don’t have to wait for the requisition.

To understand what is asynchronous in javascript read this answer:

• /a/45721/3635

Although not about ajax, this answer explains the callback:

• /a/94853/3635

And most importantly, to understand what Ajax is there is this question:

• Ajax is not a programming language. So what is?

Pro console.log work it also needs to wait for the callback, so do this:

$(document).ready(function(){
  var registroJson = [];
  var url = 'xpto';  

  $.getJSON(url,function(data){
      registroJson = data;
      console.log(registroJson);
  }); 
});